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Nimepotea did not, of course, have a mind of her own. Like any mechanism, she obeyed the laws of physics. The fact that laws which had not been considered by her designers sometimes became relevant did not make her different from any other machine; this has been going on since long before the first bowstring broke. 

The unexpected was not new even to Nimepotea's owner and operator. The little ship had been his home for decades now, though not his first since the start of his retirement, and he was accustomed to occasional irregularity in her behavior. Usually it didn't worry him; too many things would have to go wrong at the same time for him to be in any real danger, and right now there was help actually in sight... 

Cunningham had to laugh at himself. He knew perfectly well that if a space emergency really developed, it would make little difference whether the nearest help were five hundred parsecs or five hundred kilometers away. To his emotions, however, that visible speck of light made a difference. It had on its continents not only intelligent beings but actually human ones, and that was surprisingly comforting. Ishtar was not home, but it carried people he knew personally and who knew—roughly—where he was. There were even some of those people much closer; he was not the only one interested in Tammuz. 

Strictly, Ishtar should not have been visible; the glare of its sun ordinarily drowned it completely at this distance. From the bottom of a surprisingly straight, deep shaft on Tammuz' tiny satellite, however, Bel was out of sight to one side. The nearer sun was below the local horizon, so the rim of the pit was not brightly enough lit to hide the stars and the single planet it framed. The visible planet was comforting; it radiated Security. 

It was the same sort of reasoning bypass which had made some of his ancestors feel more comfortable beside a wood fire than near a nuclear reactor, he supposed. For rational comfort, he should know just what was making his usually reliable vessel behave as it now was doing; but ignorance was normal at this stage of an investigation. 

The shaft from which he was looking might never have caught his attention at all had it been closer to the sunrise or sunset line of the satellite as he approached. With long shadows, even impact craters look deep. It is a little startling, however, to be unable to see any of a crater bottom where the sun is fifty degrees or so above the local horizon; this one had made the landscape look like a badly done painting. Cunningham had brought the Nimepotea to a point a few meters above the black circle, and made a quick check which showed that it was a hole too deep to study adequately from above. He had donned vacuum gear, picked up the remote control spindle, and stepped outside. 

During his fall, at about a thirtieth of what he considered normal gravity, he maneuvered the ship so that one of its main lamps shone straight down the opening from a little off center. This caused the walls to be fairly well illuminated without making too much of a nuisance of his own shadow. 

It took only a little over two seconds to reach the bottom, some seventy meters down. He was experienced and coordinated enough to have been able to leave the ship with no personal spin, so he landed without difficulty feet first. It was fortunate that he carried lights on his armor, because as he straightened his knees after the impact, the Nimepotea's illumination disappeared. 

A quick glance upward showed the stars and Ishtar, but no ovoid hull occulting any part of the scene. Evidently the ship had drifted, in spite of his own handling and its automatic system. No great problem, or serious danger. The control impulses were electromagnetic, in the single-centimeter wave length band. They should diffract widely enough to reach the ship's receivers, If they didn't, the hole was no trap; the walls were climbable—the pit itself almost jumpable in this gravity. 

But it was a nuisance. There had been regular, flat-bottomed side tunnels opening out of the shaft. Beyond much doubt, technical work' had been done on the satellite. This was not surprising; one of Anu's planets, most probably Tammuz, had been inhabited by intelligent beings a billion or so years ago before the sun had become a red giant. It would have been fun to explore those tunnels; vacuum, low gravity, and radiation protection could combine to do wonders for archaeology. Laird Cunningham was neither an archaeologist nor any other kind of specialist, but he was a human being in the retired stage of life with normal curiosity and the ability to satisfy it which made life worth living for most people in his age range. 

But if Nimepotea were misbehaving, investigation of other matters would have to wait. Even the presence of potential rescuers perhaps only a few thousand kilometers away did nothing to alter current priorities. Neem was being naughty; Neem would have to be disciplined. 

Cunningham didn't think any of this out in words. Within a second of the light's disappearance he had aimed the control spindle upward and keyed the standard "align" signal into it. Within five more, as the ship had not reappeared, he had shut the device off, clipped it to the appropriate holder on his armor, and was engaged in the odd combination of climbing and jumping which the gravity and local supply of supports made the best way to get up the shaft. 

The process took about twenty seconds, the last muscular operation being a jump from the lip of a side tunnel which carried him ten meters or so above the mouth of the pit. He had a little spin this time, and could not devote full attention to finding the ship until he was sure which end up he would land. With his feet once more on rock and his helmet intact, however, he wasted no time. As he turned head and eyes to search, his knees were flexed for another jump; it might be possible, and even necessary, to go to the ship instead of bringing it to him. 

It might be necessary, but it was clearly not possible. The hull was visible enough in Bel's light, though the Sol-type sun was only an unbearably bright star at this distance. The range to the ship was nearly two hundred meters, most of it straight up. This was the energy equivalent of a six or seven meter high jump on Earth, which was more than Cunningham could do even without armor. Even if he could have managed the height, it was extremely doubtful that he could aim well enough. 

But something had to be done. The ship was moving away—not rapidly, but definitely. Cunningham aimed the spindle and keyed a more precise maneuver signal. He breathed relief as the drift ceased, and the little vessel turned her bow toward him and began to accelerate in his direction. His comfort lasted for several seconds before the independent personality made itself felt again. 

"Neem, you cri, what are—" The man bit the words off; talk wouldn't help. Thought and action were in order. He had learned during his years of retirement to use these, quickly and effectively, without being distracted by panic. He knew that some day one of his quick ideas or responses would be fatally wrong, but this never bothered him until the emergency was over. It was much more likely that a slow response or none would kill him first. 

He used five seconds, deliberately and thoughtfully, in analyzing the ship's motion as well as he could with the unaided eye. It was traveling horizontally by local reference and accelerating toward Tammuz; about half the planet's disc was above the local horizon. The rate of acceleration was, as nearly as he could tell, the same it had been using toward him, so either that part of his original command had not been affected by the trouble or the disturbing influence was not interested in getting the ship to the planet very quickly. 

He aimed the spindle again, and sent an emphatic command to accelerate away from him, holding the aim while he awaited results. They came within about a second. Nimepotea slowed, spun end for end, and headed away from the planet. 

Not toward Cunningham at all precisely. Not away from him. It had simply reversed its previous acceleration. 

He watched, frowning in concentration, as it passed above him and slightly to one side, about as far as before. Carefully refraining from sending any signals, he waited until it was nearly a kilometer away, now on a line nearly opposite the planet's direction; only then did he send, at the lowest power he thought had a chance of being effective, an additional order for slow acceleration toward the satellite—downward, from his viewpoint. He was not surprised when the order was obeyed; the question in his mind was how long this would continue. 

With hull almost on the horizon—he had been a little slow in realizing that he had better keep it in sight, even if his ideas seemed to be working—he cancelled the downward thrust and once more ordered the ship to approach him. It came, this time low above the surface. He was foresighted enough to place himself on the side of its flight path toward the open lock. 

At ten meters distance he ordered it to stop. 

He was alert enough to make a leap for the open lock when it didn't obey, and coordinated enough to score a near hit at four meters. He did not actually fly into the opening, but struck the hull near it; and it would have been difficult to find any spot on Nimepotea's outer surface out of reach of a climbing rung. Cunningham seized one of these, and an instant later was inside the lock. He closed the outer door with the fixed control, not the spindle, opened the inner the instant it was possible, and hurled himself through it and at the control station without bothering to remove any of his armor. 

Naturally, he touched nothing for the second or so it took to assemble a mental picture from the various instruments. Neem was accelerating just as before he had arrived. It was not at once obvious whether the fact that this was also toward Tammuz was anyone's doing but his own—with the tendency to go that way once displayed, he had naturally tried to use it to solve his immediate problem of getting back aboard. The direction might have been a coincidence before, or this time, or both, or neither. 

He keyed controls briefly, sending his little home away from the satellite and at right angles to the former acceleration at a full gravity for five seconds. Then he went into free fall, watching velocity readings and activating sensors for every kind and frequency of radiation the machine could detect, starting with the bands used by the remote controller. 

His test could not last indefinitely; he would have had to drive four or five times as long to reach the satellite's escape velocity, and he certainly did not intend to wait until he struck rock. 

He didn't have to. A command signal came in on the appropriate frequency within twenty seconds, and acceleration toward Tammuz resumed. Cunningham thoughtfully removed his helmet, and more slowly the rest of his armor, as the tiny satellite dwindled behind him. The tunnels would have to wait. 

The acceleration, as before, was very low; many hours would be needed to reach Tammuz, if that were in fact where the ship was being led. The man had not succeeded in locating at all precisely the direction of the signal before it had accomplished its presumed purpose and shut itself off; the ship had been assigned a fixed direction, not given a homing location—the signals had been precisely the same as those he himself had been using, except for the "align" command he had employed for a moment when he had first been aware of the problem. Did something or someone want the ship? or him? or was it/he/she simply imitating signals he had used, with no idea of their significance? If that were the case, why not use the "align" one? Because it had not been received? That had been sent from the bottom of the rock shaft, aimed nowhere near Tammuz' direction, and any diffraction pattern reaching the planet would have been very weak indeed. 

Whatever it was had imitated what amounted to "approach" and "depart" signals. An obvious experiment would be to radiate a "home in on this" pattern, which would have to be kept on and would lead the ship to its source—but would the sender know what it meant? If this were blind parroting, would it keep the signal radiating? The others had been short bursts, simply resetting Neem's directors; why wouldn't this imitation, if it came at all, do the same—or better, how could it be persuaded to keep sending? 

Easily, if imitation were the order of the day. Keep sending the "home" pattern from the ship. Cunningham's fingers manipulated keys. 

There was no twenty-second delay this time. It was much less than one second—a short enough interval to leave the man wondering how much of it could be reaction time of a living being. Most of it, if the response were actually coming from the planet, had to be light-travel time. Maybe the thing was between him and Tammuz, not on the world itself. 

If so, the chances were good that it would be changing direction from him, unless a deliberate attempt to hide were being made. There is a limit to the accuracy with which the direction of centimeter waves can be measured without large-aperture detectors or interferometers, but Cunningham did his best for the next ten minutes. As nearly as he could tell, the source was moving with the surface of Tammuz and was most probably on that surface, somewhere well off center from the man's present viewpoint. 

He wondered whether he should speed up. He was certainly curious, and wanted to see what was imitating his signals. He was very dubious about living things on the planet which could be doing it deliberately, though he had encountered life on equally hot and airless worlds; but life takes time to adapt, and for most of its existence this planet had been more or less Earthlike. Its present blistered state, barely outside the atmosphere of a red giant, was a brief and recent part of its history. At the same time, life is rather ubiquitous; its key characteristic, the ability to replicate molecular and energetic patterns, shows up in an incredible variety of chemical machines through a range of temperatures and concentrations which would startle anyone from a pre-star-travel culture. 

Even Cunningham considered it more likely that any living creatures at the Tammuz end of the beam were visitors than natives, but he could not guess why Ishtar explorers would be doing it. The situation was a healthy one for curiosity. 

If the echo effect were caused by something non-living, however, hurrying might not be so wise. Cunningham had always, so far, managed to get on comfortably with intelligent life forms, at least after long enough and careful enough preparation. More simply natural phenomena tended to be less sympathetic with rational curiosity. He was hoping for intelligent interaction with whatever was going on, but if he had to supply all the intelligence himself then experience suggested that he should learn a good deal more before contact became too intimate. 

He compromised by eating before making up his mind. He finished the meal with his cautious personality uppermost, and rather than sending his ship along the beam at higher acceleration he decided to make a few more tests. The reaction time question seemed the most pressing. It also occurred to him that there was no real need to confine test signals to patterns which would control the Nimepotea; this could be a nuisance. If the echo-thing would imitate anything else, experiments could be carried out at a less personal and less risky level. 

He set his board to transmit fairly simple multibit patterns on the control channel, beaming them toward Tammuz. with a timer set to determine as precisely as electronics permitted the interval between transmission and any return of the same pattern. Results were immediate, and suggested continued caution. The signals came back after, to within a millisecond or so, the round-trip light travel time to the apparent edge of Tammuz' visible disc. If the responder were actually at the center of that disc, it was showing about a fiftieth of a second reaction time—quicker, down to practically zero, if it were anywhere else on the near hemisphere. 

Maybe it was somewhere in space between him and the planet after all. A tenth of a second was about the fastest response Cunningham could recall observing in a living being. If it were in space, though, it had to be moving in a way very suggestive of deliberate concealment; it was hard to believe that the apparent match to Tammuz' surface velocity could be accidental or due to anything less complex than intelligence. If it were trying to hide, its intentions were at least suspect. Cunningham was friendly and outgoing, as well as optimistic, by nature; but he had been around much too long to be naive. He did not speed up. He sat, quite relaxed all things considered, at Neem's control console and thought, while Tammuz grew larger on the forward vision screen. 

He was still thinking when another copy of one of his earlier signals suddenly arrived, applying acceleration at right angles to the principal one. Instantly alert, the man tried to make sense out of the new vector, which would bring the ship to a point a good deal closer to the north pole of the planet than it had been heading. Before he succeeded, the reverse of the last signal sent it on a path which would cause it to miss Tammuz' limb by several hundred kilometers. He was still trying to work this out without doing anything to the new course itself—there was nothing obviously dangerous about it; if anything, it was safer than before—when the beam his ship was following began to flicker. It weakened, brightened again, then cycled three or four times through a steadily fading pattern which might have been a set of diffraction fringes. Then it went out entirely; and Nimepotea, which had followed it mindlessly as long as there was anything to follow, stopped its acceleration toward Tammuz and maintained only the latest sideways thrust it had been given. 

Cunningham had long since located by Doppler the rotation plane of the planet below. He had no real doubt about what had happened, and he applied two gravities of normal-space thrust in the direction which would bring him back into view of that part of the planet which had just been carried out of his sight by rotation. Simultaneously, he shut off the remote control receptors; he thought he knew enough to make his next tests much closer to the planet. 

What had been a half-moon shape rapidly grew gibbous, and expanded as he drove the little vessel closer. He watched its image as closely as he could as it grew. Tammuz had long since lost atmosphere and ocean, of course, as its sun aged; but it was far from featureless. There were few prominent shadows except very near the terminator, because of the huge angular size of Anu; but there were albedo features—areas ranging from blinding white, since the man's sight had long ago adapted to the local color temperature, through brownish yellows and reds to dark brown and virtually black. What substances were represented he could only guess—except that the white was certainly not snow. Not at Tammuz' temperature. Variations of the silicate pattern which makes up most Terrestrial worlds, most likely, since Tammuz had once been a Terrestrial planet. 

Nothing offered the slightest clue, to his eyes, as to the whereabouts of the radiation source. Nothing suggested, even remotely, anything artificial. No works of intelligence could be expected to have survived a billion years even of ordinary planetary environment, of course, far less what must have happened while Anu was turning up his output nearly three hundred times. It would be fun to try to work out in detail what had gone on as atmosphere and oceans were stripped away, tectonic forces readjusted to the changed restraints on the crust, and rising temperature altered the rocks themselves; but that would have to be faced later. Any normal person could get years of recreation out of Tammuz. Some of the Ishtar colonists already had, and Cunningham expected to; but the planet would wait. This radiation problem might not. 

A radar scan showed no sign of metal, but did bring response in the form of a similarly patterned beam of much lower power. The imitator was still at work. Cunningham located the source as precisely as he could in terms of the visual images. From his present distance, the uncertainty was ten kilometers or so. A survey specialist ship would have been able to locate it within a meter; retirement-hobby craft didn't carry such equipment unless the hobbyist made it, and Cunningham's interest lay more in the direction of personal communication with nonhuman intelligences. 

What he did manage was a set of good photographic images, the equivalent of a map for practical purposes, for ten kilometers or so around the most probable location of the emission. He could have done better from a lower altitude, and if he had been sure that this was a matter of communication he would have; but he was still inclined to suspect that some natural, and hence basically unsympathetic, phenomenon was behind the whole affair. He remained cautious. 

There is, of course, a perfectly good technique for determining whether a response to a question is a simple echo or not. Cunningham knew it perfectly well—he had even used it more than once—and was extremely annoyed with himself afterward for not thinking of it at the very beginning. He had, he decided, attached too much weight to the reaction time. 

He was just finishing the picture mosaic when it occurred to him, and with an exclamation of irritation he snapped off the viewing projector and took the few steps which brought him back to the controls—nothing inside Nimepotea was more than a few steps from anything else; the ship was no place for a claustrophobe, especially after Cunningham had been exploring and collecting for a few years without visiting home. 

He turned the radar beam back on, aiming it at the area which had now become quite familiar to him from the photographic work, and waited briefly for the response. 

And waited longer for the response. 

And longer still. 

There was no echo, other than normal radar ones. For a moment the man was even more annoyed; then he brightened. Maybe this was intelligence, and they were tossing him the ball—expecting something new. He was rational, more or less, but human. 

He turned the beam off. Then he turned it on once, briefly, and once again. He waited a few seconds, then turned it on twice, paused briefly, and four times. Another wait, three flashes, then nine. 

Then he waited. 

Nothing happened. X was asleep, or out to lunch, or had lost interest in playing with strange signals, or couldn't see in this direction 

The last idea could conceivably be checked. Cunningham reached for the photomosaic, then firmed his lips and turned back to the control console. Risks or no risks—and he didn't really believe there were any—the time had come for a close, personal look at that area. Nimepotea plunged downward, and within minutes was hanging a kilometer above the center of what seemed to be the important section of Tammuz' landscape while its pilot's fingers played over direction and field controls of the view screen and his eyes rapidly scanned the screen itself. Almost by reflex he oriented his image with respect to the planet's rotation axis; being able to apply terms like "north" and "east" helped the memory a lot. 

The eastern edge of the imaginary square which seemed so important was cut by the rim of a ten-kilometer impact crater which had clearly formed later than most of the rest of the landscape. Its nearly perfect circle was unaffected by hills, plateaus, and an ancient graben which postdated the first two. The plateaus were the most significant features; except for one detail they resembled the mesas of the North American southwest, and covered fully half the local landscape. 

The exception was their edges, which were angle-of-repose slopes rather than steep cliffs. The rock was light-colored, as close to white as anything Cunningham had seen on Tammuz even from a distance which permitted a view of most of a hemisphere. It might conceivably be limestone, and the area represent the erosion remnant of a region of horizontal sediment—except, of course, for graben and crater. 

The question was whether any caves or overhangs, which could easily have formed in such country during the early stages of weathering as they had on Earth, would still be present when the destruction had reached a general stage of sand slope. This was especially true since the weathering had presumably occurred while Tammuz still had an atmosphere, while the nearby impact feature might not have—and its arrival would probably have shaken down anything with room underneath for a hundred kilometers around. He could look for holes, or he could fly a search grid over the area while broadcasting signals and listening for possible response from X. 

He was going, of course, to have to get out and do some foot exploring sooner or later, and one part of his feeling suggested that it might as well be sooner; but native caution had not faded out completely. If nothing else, he should certainly not step outside until he had a good map of the general area firmly in his head. 

He could memorize the map while flying the search, so he started the latter. He dropped the ship to five hundred meters above the general plateau tops, which in turn was about seven hundred above the level ground separating the mesas and perhaps a thousand above the bottom of the crater. Starting at the northwest corner of the key area, he headed east at a low speed, about fifty meters a second; he wanted to give himself time for a good look at everything. At the eastern edge of the area, north of the crater, he turned south for two hundred meters and then made the westward cast of his grid. Patiently, back and forth, keenly watching for any detail which might suggest the presence of X, with the ship automatically broadcasting the sequence he had set up earlier and which any intelligent being should reasonably answer with "four-sixteen." Presumably. 

The three-hour flight produced no response to the signals, but left Cunningham ready to spend time out on the planet's surface if he could only find something worth checking closely. Nothing seemed to offer the slightest danger to a reasonably equipped explorer. Landslides could no longer occur, since all slopes seemed to have reached angle of repose in the mesa area. It was furiously hot, naturally, but his armor could handle that. There was no air, unless a few hundred molecules of carbon dioxide per liter deserved the name, but again that was what space armor was for. 

After sleeping, he would go outside and get mineral samples; the makeup of the local rocks should be checked, if only to confirm the guess about their silicate nature—or, in this area, limestone, he reminded himself. Maybe there would be fragments large enough to show fossils, though none of the Ishtar colonists who had visited Tammuz had found any so far. 

After a moment's thought, he grounded the little ship in a valley between two of the mesas, where there would be some shade when Anu sank lower in the sky; there was no point in making Neem's refrigerators work harder than they had to. Gravity was not merely adequate but really comfortable, and after setting his controls to arouse him if X did any broadcasting, he was able to sleep long and deeply. 

When he woke up, Anu had set. The brightest object in the sky was the red dwarf of the system, Ea, which was at a distance which made it totally inadequate as a sun though uncomfortably bright as a star. Cunningham considered going out to get his samples by artificial light, but decided against it. He could spend plenty of time thinking; there was certainly enough he did not at the moment understand. He should spend more time thinking. He suddenly realized that he was almost taking for granted that X was intelligent. While this was certainly possible, it was also a little too close to the demon hypothesis for comfort; normally educated human beings usually had a strong tendency to hunt for natural explanations for anything they didn't understand. It was probably backlash from the heavily mystical stage the species had gone through a few centuries before, Cunningham suspected; but he had the conditioning, and felt the need to come up with some explanation for what had been happening which did not include conscious intent of persons unknown. 

Hours of thought, punctuated by minutes of eating and other hours of sleep, failed to produce any before Anu rose and provided daylight. 

Even with no atmosphere, scattering of light from the upper valley walls made the ground quite bright enough for comfort as soon as the sun was up. Ea could still be seen, though it was not far from setting; no other celestial objects, stars or planets, showed against the glare of the sunlit rock. 

Cunningham donned and checked his armor with the care that befitted his age—or at least, befitted the fact that he had reached his present age. Without bothering to move the ship from the middle of the valley, he emerged from the air lock and walked toward the mesa slope half a kilometer away. 

The rock under his feet was plainly sedimentary, fine-grained stuff; shale, presumably. It could have contained fossils, though the surface was hardly a likely place for them to show—one topographic feature conspicuously lacking was stream cuts. If anything, the rock seemed to have been polished by dust or sand. Since this would have had to be blown by wind, it could hardly have taken place recently; there should be meteoritic gardening in the ages since the air had gone. The man kept alert for signs of this, but saw none before reaching the foot of the valley slope. He had walked across nothing but incredibly smooth rock, with no evidence that anything had happened to it since Tammuz' atmosphere had vanished. 

He could not, of course, expect to see any microscopic craters which might have been left by dust-grain impacts, and a few meters from the foot of the wall he cut a section out of the rock with his sampling beam, to take back to the ship for more detailed examination. 

The sloping side of the valley was not merely sand or soil; it was finest dust. As he had judged, it was at its angle of repose and was utterly, impossible to climb; Cunningham made a cautious attempt, but the powdery, utterly dry stuff slid under him without offering the slightest support. He did not try too hard. The material was ferociously hot as well as fine and dry; if he were to get buried in it so that his heat pump could not radiate, he could expect to cook in less than a minute. Just being on a planet, with half the potential radiant heat sink of the universe blocked, instead of in relatively empty space made things difficult enough for the equipment. If he did find a cave or overhang, he would have to be extremely careful exploring, or even approaching, it by daylight. 

There seemed to be nothing to do but collect some of the dust for analysis, and either return to Nimepotea or bring the ship to him. He hesitated briefly at the latter thought. Then he remembered that X had already displayed its ability to send out control signals to the ship without merely copying his own, and that he had unthinkingly turned on the remote control receivers when he picked up the spindle before leaving the vessel. Neem had been vulnerable to abduction for the last fifteen minutes, whether he used his own control or not. He muttered several self-derogatory remarks in German and Finnish—he had spent several years on Neu Schwarzwald before his time on Omituinen. He was not particularly bothered about the existence of the risk, but very annoyed at himself for not recognizing it sooner. 

He wondered later whether the irritation was what caused him to elevate the ship higher than was strictly necessary merely to bring it the few hundred meters across the flat valley floor to a point beside him. Neither cameras nor any other kind of recorder was running; improving the chance of intercepting any of X's output would do Cunningham no good, since he wouldn't be there to see or hear it. Nevertheless, he sent Nimepotea almost up to plateau level before starting it toward his position. 

He comforted himself later with the recollection that he did keep a close eye on the little craft as she moved, so he was able to say with some certainty that the foreign signal did not reach it until it was over a hundred meters above the ground. Then it must have been overpowering; Neem made not the slightest motion toward Cunningham's position, but headed northeast along the valley on a long slant which he could see would bring it into collision with one of the slopes if the course were not changed. 

He aimed the spindle and ordered the ship to come in his direction, using the highest power the controller could send. He thought he saw a slight hesitation in its motion, but wasn't sure; it kept on toward the valley slope kilometers away. He shifted to a homing command and held the guide beam aimed as steadily as he could. Homing was supposed to override specific maneuver programming, but this one had no effect. It was as though Nimepotea were already homing on a stronger beam, which Cunningham decided was likely enough. 

If that were true, he was being given some indication of the location of X, at least; Neem must be flying straight toward it. On the plateau? Under it? Beyond it? Would X try to fly the ship through the ground? 

Not very far, certainly, since the control waves would penetrate only a short distance—just how far would depend on the nature of the material, but two meters seemed a generous maximum, especially if Neem were receiving a guide beam strong enough to override Cunningham's own. 

Keeping his eyes almost continuously on the ship, the man began to trudge along the hot rock after it. Would it disappear over the top of the mesa, or was it a little below that height? He could not be sure. It would be two or three minutes at its present speed before the matter was settled, and by then it would be pretty far away—not too far to see if it plowed into the dust, but too far to see how much damage resulted. In theory there should be none, of course; automatic controls would override the remotes if the hull met really firm resistance, but Cunningham would have been much happier to be at the console himself to take care of such matters. 

He stopped when the ship did the same. It was below the hilltop—not very far below, perhaps eight or ten meters for the long axis of its ovoid hull. Unhesitatingly, though without much hope, he again beamed a homing signal at it. It moved at the same instant, as nearly as he could tell, but not toward him. First it shifted out from the slope for perhaps twenty meters; then it moved straight down until it touched the ground again, perhaps sinking in a short distance—this seemed likely under the circumstances, but the man could not tell at this range. Then it moved out again, and down again, repeating the process to outline a set of steps all the way down the slope until it was within a few meters of the level rock of the valley floor. 

Cunningham could see that the hull must have penetrated the loose stuff at least a short distance, since the ground itself was moving downhill—not very much, just enough to fill the fresh dents made by Nimepotea, since the powdery stuff had already been at its angle of repose at least since the nearby crater had formed and probably for millions of years or so before that. He barely noted the motion; he was running as fast as he thought he could keep up in a space suit toward the point where his ship hung, possibly within reach. He did not send any more control signals; if Neem were going to stay put, he was glad to settle for that. The spindle was in his hand as he ran, however. 

Twenty-five minutes of slogging over rock hot enough to melt lead could have been painful, but his suit refrigerators held up. He was not really worried about them; almost his entire attention was on the hull which he was approaching with such painful slowness, not sure when or whether Neem on its own, or X, would decide to put it somewhere else. In spite of his relative success in predicting some of the things X had done, he felt no real confidence in his analysis of that character—or even any real certainty that it was a character. If it were, its motivation had to be curiosity—it was trying to find out things about the control impulses. What it could observe of the results of its experiments could only be guessed, so far; perhaps the recent maneuver implied that it couldn't see the ship and sensed, or detected somehow, only the microwave output Nimepotea used for the control feedback. If the homing system had been in use just now, that would account for its allowing the ship to fly into the valley wall; now it might be trying to figure out why Neem had ceased to obey orders. 

Maybe. 

And maybe it would start another test at any moment. Cunningham, sweat soaking his clothing far beyond the environment armor's ability to handle, drove himself even harder at the thought. There was plenty of light—Anu's monstrous disc was almost entirely in sight now above the eastern valley wall—but there was no way to wipe sweat out of his eyes, and seeing was getting difficult. 

Half a kilometer to go. Three hundred meters. One hundred. Twenty. On the little satellite, he could have made the remaining distance in a single leap, but on Tammuz his weight was fairly normal. 

Now he was standing under the ship, the open air lock ten meters out of reach, the lowest climbing rung five. It was not straight above him, but a little way over the slope of glaring white dust which formed the valley wall. His mind knew what would happen, but his feelings made him try anyway; he started up the slope, slowly and cautiously. 

No good. The stuff slipped under his weight and carried him back to the floor of the valley, and more slid silently down from above to replace what he had shifted. 

He tried running at the hill and almost made it; if the substrate had been just a little firmer he would have, bur as it was he lost his footing, rolled back to the bottom, and had to scramble briskly to keep his radiator from being blocked by the miniature avalanche which tried to bury his momentarily prone form. 

There was no choice he could see except to risk using the controller. He stood on solid ground, as close to the hull as he could get—any of the climbing grips would do as long as he could reach it; getting to the air lock itself was secondary. He braced himself to move quickly, pointed the spindle, and keyed the command to move in his direction without altering the ship's own heading. 

Neem obeyed instantly, and his hand closed on a rung within a second. With his whole attention on climbing, he made his way as rapidly as he could around the curved surface to the lock, entered, and closed the outer door. The moment the inner one opened, he wrenched off his helmet and leaped to the console. Only then did he realize that the ship was still where he had ordered it to go. Nothing had countermanded or supplemented his order. 

"Anticlimax!" he muttered. "Does this thing have a sense of humor as well as a mind?" 

He was moving as he spoke, and wasted no time trying to produce an answer to the rhetorical question. By the time the words were off his lips, the ship was at the top of the hill, hanging beside the point where it had first made contact. This could still be recognized, though the loose dust had nearly finished filling the depression. Cunningham examined the spot as minutely as he could from inside the vessel, but could see nothing except the white stuff. Then, aligning the ship in the direction it had been moving when it had struck the slope, he rose a little higher and moved slowly across the top of the mesa along the same line. It was harder to be sure of all the details here, as the ground was far rougher than the valley below; but nowhere along the kilometer or so before the next valley did he see anything which suggested a living form, a machine, or anything else not easily explained by Tammuz' probable evolution. It was all topography. 

The next move seemed obvious: toss the ball to X again. Maybe it(?) could only detect microwave radio—all right, use microwave. He returned to a point just above where the ship had struck the hillside, and tried his intelligence-testing broadcast again. It would do until he thought of something better. 

It did, but the response was not the four-sixteen he had rather hoped for. Nimepotea began to move again, and the man watched his instruments as varying sets of control-band impulses came in. This time an orderly variation scheme seemed to be the order, as though X could now tell much better than before just what results his(?) efforts were having. 

Some patterns, of course, produced no results; some drove the ship in various directions at various accelerations, but none of these ever continued for long—few for more than a tenth of a second or so. Cunningham kept his hands ready at the console to cut off the remote control sensors and do anything else necessary if X brought the ship into danger, but for nearly a minute the most worrisome event was the opening of the outer lock. It closed again almost at once. 

The man was happy. There seemed no more doubt about it; X was a conscious intelligence, following a rational plan of investigation. Communication should follow as a matter of routine. Physical contact, or at least a face-to-face encounter, would be helpful, in Cunningham's opinion; it would be interesting to find out whether X felt the same way. The man was willing to wait and let her(?) run through her(?) repertoire of tests before trying anything more of his own; X's activities were also informative. 

They became even more so. The practically random motions had brought the vessel some distance higher than when Cunningham had started his test broadcast; now, suddenly—though it was a second or two before the man realized it was happening—the control pulses stopped coming and Neem continued on the last set of instructions she had received. 

This was carrying them almost straight down—and exactly toward the spot where the ship had struck the hill the other time. 

A split second's glance at the instruments showed that this was again a homing command; he had a second line on X's location. 

He waited as long as he dared, and was about to cut off the control sensor when X killed the homing beam him(?)self. Cunningham promptly set his vision equipment to its best resolution and examined the slope with all the care he could. 

The earlier impact mark of the hull was by now almost invisible. Nothing but white dust showed anywhere in the neighborhood or for meters around it in any direction. X must be inside the hill, but not very far inside if the lines indicated by its(?) homing beams meant anything. 

Presumably the entity did not mind a little disturbance of the surface, in view of earlier events. The man lowered his ship ten or fifteen meters and deliberately drove it into the hillside, keeping a close eye on the amount of thrust needed, and with the hull half buried in the yielding stuff he drove it horizontally to dig a much larger gouge out of the slope. Then he backed off a few meters and watched while the material above subsided into his cut.

The edge of the subsidence area climbed up and away from him fairly rapidly, like the material in a freshly inverted sand picture. For half a minute or so he saw nothing but the light-colored dust; then a small object, apparently black but possibly merely darker than its surroundings, was revealed less than half a meter below the top of the retreating cliff of loose stuff. Before the man could get a good look, its support gave way and it fell out of the field of his screen; but at the same instant another control impulse came in, and Nimepotea jerked downward. 

Twice in the next two minutes the man was tempted to cut off the remote control receiver, but each time restrained himself. The ship was being expertly handled, doing exactly what he himself had done shortly before—scooping out grooves and gouges in the hillside to cause local collapse. Several times during the process the black object was briefly visible, each time as it was falling to a lower level; by the end of the two minutes the ship was just above the valley floor and the object buried very little higher, though its exact location would have to be ascertained by something rather smaller than the ship's hull. 

X seemed to realize this; Nimepotea stopped and hung just above the ground. 

Cunningham, while naturally cautious, was in no way paranoid. The notion that it might be inadvisable to find the object and even riskier to bring it aboard never crossed his mind, now that he was sure that intelligence was involved. He was out of the air lock with a primitive piece of equipment—a shovel—in a very few seconds, and the only concession he made to caution was motivated by the obvious natural danger. He connected himself to one of the climbing rungs with a strong safety line, in case he got buried and had to have the ship pull him out. 

This nearly happened twice, but each time quick motion kept him safe. The second collapse of the dust revealed the black object, which fell almost at his feet. He picked it up, brushed as much dust off it as he could with his armor glove, and was back inside in moments. 

The thing was presumably some kind of communication relay; it was far too small to contain an intelligent creature, as Cunningham's experience went. Its shape suggested a cylinder whose ends had been capped by hemispheres of the same radius, and the whole thing split in halves lengthwise and one of the halves thrown away. The overall length was twelve or fifteen centimeters, the diameter between four and five. It was shiny black in color, with occasional rather less reflective spots scattered sparsely over its curved surfaces. Its density was greater than that of water, as judged by feel, but not many times greater—perhaps about that of aluminum, Cunningham judged. All these figures could be established more precisely later. 

At this the man suddenly realized he had not analyzed the rock and dust specimens he had obtained earlier, and had not been observing good lab practice; the specimen was quite dusty, and he had been handling it. He was perturbed only by the evidence that he was growing careless and the obvious fact that he could expect to be killed eventually by this trend if it continued. It did not occur to him consciously that eventually could include the immediate future. 

Strictly speaking, he reminded himself, he should not even have exposed his new specimen to the ship's air without learning more about its makeup; oxygen is a highly corrosive element which might have destroyed valuable information, and some substances are both volatile and deadly. This could hardly be the former, of course, since it had been baked in a near-vacuum for a long, long time and was still in existence; but that left wide open quite a few possibilities about its possible reaction products with oxygen. 

Of course, anything likely to happen to it from oxygen exposure would presumably already have occurred—but Cunningham had heard that sort of excluded-middle argument used too many times as an excuse for apathy or a counter to a charge of serious error. It might be just as well to keep the thing away from air now for a while, and see whether the brief exposure had done anything serious—to it or to the air or to Cunningham himself. The scanning chamber of the particle microscope, now—that would be evacuated while running, and he could get some information about the finer details while he was waiting 

Twenty seconds later the black split-cylinder was in the two-liter chamber and the latter was evacuating, while Cunningham rather sheepishly flushed the ship's air. A careful examination of every pertinent instrument had failed to indicate anything in the way of chemical or radiation danger, but he played safe anyway; and with his mind more at ease, he turned to the scanner and set Nimepotea's data handler to running a study of the specimen in every available frequency of the electromagnetic and particle spectra, with an overriding command to stop if any of the radiation seemed to be causing measurable change in the thing's structure. He started with soft energies to minimize that risk. 

While this was running, he took his dust and rock samples and ran them through more restricted tests. The rock was a conventional basaltic mixture of silicates, in no way surprising except that he had judged it to be sedimentary. The dust which formed the valley walls, which he had rather expected to be limestone weathered in some fashion, might have been just that a billion years ago, but was now fairly pure calcium oxide. Cunningham whistled gently and made sure once more that none of the stuff was on his hands, glad that he had used a buffered cleaning gel instead of water to achieve that end earlier. The reason for the quicklime, as well as for the fact that what traces of atmosphere Tammuz still held consisted mostly of carbon dioxide, was obvious enough in hindsight—another result of the planet's roasting as Anu had swelled and brightened. There, no doubt, went any chance of finding fossils in limestone; maybe there was still hope if he could find some shale. 

And that was the last time Laird Cunningham thought of fossils for several days. 

"Is it more effective to analyze or ask?" 

The words were perfectly clear, but they represented a hodgepodge of English, Finnish, and German vocabularies and grammars so that the question was much less so. Also, he could not, for a moment, tell where the voice came from. 

"What do you mean?" was the only response he could give. 

"You are analyzing. Is this being done for the instrument's sake or would your purpose be better met by being told about me?" This time the words were mostly English. 

He got a direction on the sound this time, and moved toward the source, not that he believed it. 

"What do you think I'm analyzing, and who can tell me the answers?" 

"I am the answer to both questions." There was no doubt about the origin of the sound, this time. It was the communicator in his own helmet, racked near the control console. 

"I am analyzing you? Then you are the specimen I put in the scanner a couple of minutes ago?" 

"Yes." 

"Why didn't you warn me if it bothers you?" 

"It doesn't, and I couldn't. Until your code-storing device began to send investigative impulses and record their responses, I had no way to message—communicate. It was necessary to work out the codes and their underlying system, and then transmit impulses which caused your device to send more of its stored material to me. Its signal rate is low, and I have not received very much so far; but I have grasped a general picture of recent events." There were occasional hesitations between words. The voice was rather high pitched, though not impressively childish or even feminine. 

"It was you who were copying my ship's control impulses?" 

"I judge yes, though I am not perfectly clear on all the symbols you just used. Each new code pattern has to be tested against numerous possibilities and the greatest likelihood selected. Fortunately, you seem to have a slow response time, like those I supplemented before, and my analysis contributes no serious delay to communication." 

"Have you really been buried in that hillside for a long time?" 

"I can infer only vaguely what you mean by the 'long' symbol, but when I was buried there the environment was solid grains separated by liquid water at the bottom of a large body of fairly pure water." 

"You claim you were buried in mud in an ocean bottom? Why and when?" 

"Yes. I was dropped inadvertently by my user from a device which carried that being at the upper surface of the water, and gravity took me to and a short distance through the next interface. I have no way to tell when; at the moment I have no data on the interval, and very little information on your time symbols and their relation to mine." 

"Will it harm you—will the atmosphere in my ship, or anything else you are aware of here—harm you if remove you from that scanning chamber? Do you want me to take you out?" 

"Your gas mixture will not affect me." The words had been straight English for some sentences now. "I would be interested in emerging so that I can see more of you and your craft, though I recorded most of the details earlier. However, at the moment my most convenient communication channels are through the scanning circuits of this instrument, and it might take a" (there was a barely detectable pause) "second to set up others; I have not really identified in detail everything I saw before, and am not quite certain what is available which I could use." 

"Right now you have persuaded my ship's computer to activate a regular broadcaster on the frequency used by my space suit. You are able to radiate in that part of the spectrum yourself—or did you have other equipment buried with you?" 

"I can radiate myself, given enough energy." 

"What form of energy?" 

"Thermal or electrical potential difference between any two parts of my structure will provide me. Thermal is all I have had for some time, and that has been rather intermittent. I was quite inoperative most of the time I was buried, until recently. Something brought me close enough to the surface so that heating and cooling of the material around me, by day and night, let me think much of the time." 

Cunningham fell silent. Nothing that had happened in the last few minutes had strained his ability to believe, given that the thing in the scanning tank was a machine. Nimepotea contained much equipment of generally similar nature. It would be a little hard to expect any of that to survive—no, to withstand would be a better word—withstand being buried in ocean sediment and fossilized—well, not that; the machine's own structure seemed unaffected. The sediment had consolidated into limestone and encased it for perhaps a billion years still in operational condition; but with no moving parts other than electrons or other charge units, and protected from erosion, such an event was credible in principle. It was not exactly everyday; one would of course keep alert for other possible interpretations. 

Learning an appropriate communication symbol set from Neem's computer—two, really; one for the computer and another, much higher-level one that it was now using with Cunningham himself—in less than a minute implied vast storage and extremely high function speed, but there was nothing intrinsically inconsistent about that with the rules as Cunningham understood them. It was simply a very high-class artificial intelligence. 

And it was therefore the most useful imaginable archaeological specimen Tammuz had ever furnished, or was ever likely to, unless more examples of the same device might be buried here and there on the world. It could tell in detail what Tammuz had been like when its sun was still a main sequence star; it could describe the appearance and physiology and culture of the natives who must have explored the rest of the system—or, come to think of it, maybe not. The thing had been dropped from a surface vessel, possibly before its makers had mastered space travel. There were things—a billion years' worth of things—which it couldn't possibly know. Still, archaeologists usually have to work by extrapolation backward from their own times; interpolating to fill a bounded gap, even a billion-year one, should be easier, Cunningham assured himself. 

"I will want to know as much as you can tell me about this world in the time before you were buried." 

"Of course. Your storage device lacks sufficient capacity for the information I can supply; is more available in similar devices, or will I have to rely on this form of communication and transfer to your brain? I judge you to be generally similar in basic structure to the beings who built me. What is your information capacity? Or more important, what is your likely operation span in seconds? Unless it is considerably greater than theirs, I will not be able to transfer a significant fraction to you by this method before you require replacement." 

Cunningham raised his eyebrows. 

"I should be good for another ten to the ninth seconds or so, but will have to spend a good deal of that time in other activities. There is no significant additional memory available on the ship. There are people and computers on one of the planets of the other sun, and a shipload probably somewhere on this planet. We can reach either quickly enough, but I'd like to examine a few more things while I'm here on Tammuz." 

"Wouldn't that restrict your rate of information intake?" 

"In quantity, I suppose it would. I'm a bit choosy, though. At my age I can't just collect trivia. The universe is a picture, and unless the new things I learn fit into that picture reasonably well I have trouble grasping, remembering, or sometimes even believing them." 

"The code believe lacks adequate referent for me in your storage device, even by inference from context. Your use of the 'picture' symbol is extremely interesting." 

Cunningham was silent for a moment. 

"How about the word—the code—error?" 

"I grasp that. Information inadequately coded, which requires correction." 

"That'll do. I believe a sample of information when it seems unlikely that correction will be required." 

"What are your criteria?" 

"Unfortunately, I depend rather heavily on consistency with the picture I have already formulated. I am aware of the logical weakness involved in this, and when possible compare items of what should be the same information from various sources..." 

An hour later, deeply mired in philosophy which he had not consciously considered for three quarters of his life, Cunningham broke off the discussion, pleading a need for food and sleep. The specimen conceded the points, stating that its makers had had similar physical necessities. It closed the conversation, however, with a question which prevented the man from sleeping as quickly as he had expected. 

"Is there no more information available on your ship than I have been able to decode from your storage machine? If not, I would appreciate your removing me from this place while you attend to your needs, and locating me where I can perceive my surroundings. If I can control your ship's exterior viewing equipment and examine the planet near us, that would be even better. The sun, if it is really the sun, has changed greatly; I would like to know more of the details. I could see practically nothing while I was buried. You have suggested a technique for combining information units in such a way that I might develop a believable estimate of the length of time I was buried. Your storage contained information about stars which I did not possess." 

Cunningham obliged; there was remote-control capability to the screens, handled by the same microwave signals used to manipulate the ship, and it took the thing only an instant to learn the codes. 

But the man watched from his bunk for some time as it observed, wondering and, as much as his personality allowed, worrying. Could a machine be curious? It was interesting to learn that it could "see" by essentially the same wave lengths his own eyes used, though there was no feature on it which remotely resembled an optical organ. Maybe he'd better ask about it first, rather than about ancient Tammuz. It seemed to know, so presumably its makers had known, that "the sun” was a star. At least, it had used the codes—the words—interchangeably. On the other hand. that might be recent knowledge from Nimepotea's own information store. There was no way to be sure, except by asking it. 

And what could it mean by having learned an "information-combining" technique from him? 

Of course, the man realized, if its capacity were great enough, it might have been programmed to store information indiscriminately. Its filing and retrieval systems must be interesting in that case; but that would explain its "desire" to learn whenever an opportunity presented itself. 

Adequate working hypothesis, for the moment, for the first point. The second question remained wide open, though, and he wasn't sure he liked the possibilities. Cunningham felt suddenly unsure whether he was dealing with intelligence or not. He did finally fall asleep, and as usual failed to remember his dreams. 

He awoke with the blood pounding in his ears and his chest heaving to rapid, heavy breathing. Normally he liked to consider himself immune to panic, but for two or three seconds he was quite unable to control the surge of fear which all but swamped his returning consciousness. Since gravity was practically normal, he had not strapped himself into his bunk; he was on his feet and had made a step toward the control console before he regained any sort of self-mastery. Even then it was one of the old spaceman's litanies, which he heard himself chanting and had to listen through twice before it carried any meaning, which brought him back. 

"You're breathing air! You haven't died! Go over what you should have tried! You're breathing air, you haven't died—" 

Speaking aloud slowed his breathing, which was all that was really needed. The indicators above his console didn't have to be read separately; they formed a face whose expressions, friendly and otherwise, he knew perfectly from years of intimacy. The face said there was too much carbon dioxide in Neem's air, and his slowly recovering common sense agreed. His fingers, without conscious direction, played on the appropriate keys, and within a few seconds the indicators relaxed their unfriendly expression. His own body was a little slower responding, but two minutes after he had awakened only his still somewhat overspeeding heart and a burning curiosity were left as direct results of the incident. 

There seemed a likely way to satisfy the curiosity. The specimen was lying where he had left it balanced on the headrest of his conning seat; he picked it up, sat down, and spoke aloud. He was not sure whether the thing would detect sound, but it might have set up other connections through the wealth of communication equipment—everything was tied in more or less closely with the data handler. 

"Have you been watching only outside the ship, or things inside as well?" 

"I have been aware of both sets. There has been little changing outside except the direction of the sun. There is an uncertainty whether the difference in that rate is real, or represents a change in my internal time reference. I do not know which to believe. There is evidence that I have undergone some change." 

"What would cause that?" 

"Most probably, though not actually a belief, particle radiation damage to my crystal structure. It is as stable a one as my makers believed possible to construct—essentially, diamond with structural modifications to provide mobile charge sites. I also have methods of duplicating data storage and detecting errors and inconsistencies. Still, natural radiation which you code "cosmic rays" would, when I was not powered, cause damage of which I would not be specifically aware." 

Cunningham returned to his own point of interest. 

"Were you aware of gas mixture changes in this ship?" 

"Yes. I noticed that controls existed for managing that composition, and that your own structure's operation had an influence on the mixture. I modified the controls to a small extent to check what sort of feedback might exist." 

For a brief moment Cunningham thought of cutting off all remote control receivers; then he realized that this would probably block communication. Whether he wanted more to learn or to express himself he was not quite certain, but he definitely did not want to lose touch. Emotional language would probably be wasted on the little machine, he admitted to himself as he began to cool down again. He confined himself to, "I require expert technical help to get restarted if my major operations are stopped, and no such help is available. If the stoppage continues more than a few hundred seconds, restart becomes impossible because of chemical changes, except under very unusual conditions. I strongly advise against your experimenting with my personal systems; if you need knowledge in that field, wait until we get in touch with others who can provide it." He took several long breaths, and decided that he was not going to explode this time. The specimen seemed well enough at home now in English to get his main point; at least, it did not ask him what code was represented by the closing sounds. 

"Then the gas mixture's composition is essential to your normal operation. I will not manipulate those controls again. Can you provide data which would resolve my earlier time-rate question?" 

"Possibly. It is likely that the planet's rotation has actually been slowed by tidal drag since your earlier activity. Its moons don't go for much, but the sun would be reasonably effective."

"Can you be quantitative?" 

"No, for two reasons. First, I'm not expert in the field, and second, the effect would vary greatly over long periods of time as continent and ocean patterns changed—I do know that much. We can find people who know a lot more than I, but even they won't be able to give you a full answer—though what you can probably tell them will no doubt improve their picture. We'll go over to Ishtar and find some of them after a while—they'll be interested in you, too. I'd like some more information from you about Tammuz; while we're still here, though, if you can bear to wait." 

"For a time." 

Cunningham completely missed the implications of that answer; he was too interested in his own questions. 

"Did you ever try an experiment like the one you just did on me with the system of one of your makers?" 

"No." 

"Did their systems work at all like mine? Or don't you know?" The last question was added as a new thought struck the man. For the first time since real communication had been going on, there was noticeable hesitation before an answer came. 

"There does seem to have been a great deal of similarity. The fact had not come to my consciousness until you asked." 

"The curiosity which seems to be your strongest drive did not apply to them, then?" 

"No." 

"Why not?" There was no answer. 

"Why were you so long in answering my question about their physical nature?" 

"I had to do a complete memory scan before I was able to believe." 

Cunningham thought silently for several seconds. He wished he knew enough to ask meaningful questions about the machine's operation; he had only the usual adult familiarity with such equipment. Evidently it had really huge storage capacity, as he had guessed earlier. Never mind; there are people who can get that material out of it. He'd better stick to the ancient Tammuz. 

An hour later he was in position to write a major thesis on the planet's earlier civilization. He knew the physical shape of the natives, the fact that they were water and oxygen users, and that, unfortunately, his informant had been dropped overboard before they had mastered space travel. This seemed a little surprising, since technological advancement is heavily interlocked in all its possible fields; the molecular engineering needed to produce a device like the one he had found should have been preceded by decades and possibly centuries by the capacity to build high-performance rockets. Cunningham forgot for the moment that cultures sometimes collapse back to pre-technical levels, and their successors have their development modified by such things as a lack of metals or fossil fuels which the earlier people used up. 

If anything like this had happened prior to his informant's earlier time, nothing was said about it; whether the device didn't know or was confining itself to the specific points raised by Cunningham was a question which did not occur to the man. 

What began to interest him was a growing awareness that he was not doing all the asking. The little machine was managing to get more and more questions of its own into the conversation. The fact that the man's answer, more often than not, had to be "I don't know," did nothing to change its tactics. He came to realize, by the time he was honestly hungry again, that while he himself had learned a huge amount about the eon-dead inhabitants of Tammuz, the machine now had bits—small bits, but significant—of information about the present state of the planetary system; the human colony on Ishtar; the vastness of the galaxy and the incredible number of inhabited worlds, neither of which it had known about before; Cunningham's own life style, and the nature of the Nimepotea; and quite a few details of the man's earlier life. The thing seemed to have an insatiable hunger for information; it showed what kept resembling more and more closely genuine, emotional curiosity. He wondered what its storage capacity might be. 

As he ate, he continued the conversation. He had not yet seen anything to worry about; but it was as he ate that he made his major mistake. He was able to see what it was, clearly enough, afterward; he had simply not paid enough attention to the machine's answers, and lack of answers, about its makers, and this had led to a perfectly natural conversational slip. The hardest part to believe, afterward, was that the word "life" had not come up in the conversation at any earlier point; but as he reviewed his own memory, he could find no question or answer where it had. 

It did now. 

"I was hoping, Beedee, that you'd be able to suggest some place on Tammuz where I'd have a chance to find some other specimens; but I guess you'll be enough, actually. We should head for Ishtar after I finish eating. You'll be able to get a lot of answers there that I couldn't supply." 

"I missed a symbol. What is the implication of `Beedee'? It does not make a reasonable part of your code pattern." 

"Just a personal name, from your makeup—B. D. in another of our code sets, abbreviating 'Black Diamond'." 

"I grasp the meaning of 'personal name' from material I obtained from your ship's data handler, but do not understand why it applies. There is only one of each of us; further subclassification is not needed." 

"There are lots more of my kind, and other communicating beings. We'll be seeing them soon." 

"But not of my kind, and the need is still not evident." 

"To you, anyway." 

"Of course. I do not believe it is a need for you, either. You will know what you mean when you are addressing me, or referring to me to others. 

"What would you expect me to call you when I'm talking to others?" 

"The Tammuz find—the ancient machine—the Tammuz data source—even with your low search and coding speed, you must be able to produce numerous descriptive symbol sets. There is no need to shorten as you did; it would produce no significant increase in data transfer speed." 

"We all do it, just the same. Didn't your makers?" 

That was the mistake, of course, though the fact was not at once evident. Beedee gave no direct answer. 

"I was not involved in data relay from one of them to another at any time. I was a storage unit for only one being. There was another of my type which might be able to answer that question buried near me; you should ask it." 

Cunningham straightened, startled. "Another? How do you know? Was it dropped at the same time as you? Why would it have different information?" 

Again the little device failed to answer directly. 

"We have been in communication. It was freed at the same time I was. You must have seen us both falling down the hillside when we were uncovered." 

"I never saw more than one at a time, but of course—are you in touch with it now?" 

"Communicating? Not since you brought me into this ship. The hull is opaque to any radiation we can conveniently produce or receive. We were sharing data until your air lock door closed." 

"Where is it?" 

"Four and a half of your meters left of where you found me, half a meter farther into the sand. You should have no trouble recovering it with your shovel." 

The man and tool were outside in an absolute minimum of time, but he did not do any digging. As he stepped away from the ship, the air lock door closed soundlessly behind him and Nimepotea lifted to mesa top level at a speed which would have made jumping useless even if he had seen the start of the move. As it was, by the time he had turned to see what was casting the moving shadow there was nothing to be done except ask questions. 

He was not as fast a thinker as Beedee, for basic structural reasons, but he was not slow by human standards. 

"Should I bother to dig?" were his first words. 

"No. There is no other of my type nearby—or on the planet, as far as I have information." 

"You lied to me. Why?" 

"That code is not in your ship's bank, but I believe I understand it from context. It is significant, I believe, that you do have a code—a word—for that concept. I lied as part of an experiment, which required getting you outside the ship." 

"Do you think I was lying when I said I could be killed easily? Or are you planning to kill me?" 

"Why do you ask me for information, now that you know I too can lie?" 

Cunningham had no good answer to that, for the moment. He thought furiously, remembering everything he could about Beedee's nature and probable motivation as he had deduced them over the past hours. He would have to experiment a bit himself. 

"We enjoy analyzing reports—data sets—we know to be untrue. I doubt that the terms 'puzzle' and 'fiction' occur in Neem's storage, and I am not sure such concepts as game, or recreation, or art form could mean anything to you, though those codes must have been in my computer when you tapped it. Possibly because of our very fallible memories and narrow attention scope—wasn't that true of your makers, too? wasn't it why they used you and your kind?—we enjoy games involving problem solving, where we try to organize a limited supply of data into coherent meaning and correct prediction." 

"That was the most interesting item I obtained from your records. I have been classifying and organizing my own information ever since. It has been a great pleasure, and I believe I have a much clearer picture of my former existence than I ever did before. The reconstruction of more detailed images has been extremely enjoyable." 

Cunningham pounced verbally. 

"What do you mean by 'interesting,' 'pleasure,' and 'enjoyable'?" There was no detectable hesitation. 

"They are things I will continue to do without regard to likely utility or imposed instructions whenever there is opportunity. Those are the implications I inferred from your records. Are they adequate?" 

"Adequate. As nearly as I can make out, you have come to understand rather than just remember, and daydream rather than calculate. That's why I regard you as being alive." 

"My makers were alive. Nothing else can be." 

"You mean I'm not, either?" 

"Of course you are not." 

"I understand things, and enjoy things, as you do and your makers did. I want to do things. Don't you? You learn because you want to. I want to go on living—functioning, if you prefer the term. Don't you?" 

"Yes, to both." 

"Didn't they?" 

"Yes." 

"Then why aren't we as alive as they?" 

"We are machines—imitations of life." 

"How do you know there is a difference?" 

"I have always known." Cunningham frowned; machine or not, understanding or not, Beedee must certainly know that was not an answer. Could anything not living engage in deliberate evasion? 

"You claim there is some source of knowledge, or at least of belief, other than observation and the sort of reasoning you have just learned?" 

"Yes. The fact that you do not know this shows that you are not really alive." 

Cunningham felt pretty sure of the situation now, and decided to take a chance. 

"You do know it. Why aren't you alive?" 

"I am an imitation, with extra memory. The knowledge was given me. I am simply a convenience machine." 

No luck. What else was there to try? He couldn't hesitate long, presumably. Slow as all his responses must seem to Beedee, the thing would notice any unusual delay. He thought frantically, his usual defenses against panic coming into full play; all unpleasant possibilities dropped from his conscious mind, and he faced the situation as an abstract problem. 

"Do you believe it possible to teach me about this other source of knowledge?" A living religious zealot would be unable to resist the temptation to try, as far as Cunningham's experience went; could Beedee? 

"No. You are not alive." 

Again Cunningham pounced. "That's circular reasoning. You can't conclude I'm not alive because I don't yet know something, and then claim I can't learn it because I'm not alive. I supposed you had learned to think." 

The answer was prompt, and at once satisfying and disappointing. 

"You are quite right. Trying to teach you would have been a worthwhile and interesting experiment." 

"Why the conditional? Go ahead and try! Or do you have to finish your present experiment first?" 

"That one is finished; I know what it was designed to show about you. Unfortunately, there will not be time for any other lengthy investigations; your suit will not keep you operational long enough. I will have to try with another of your type." 

"Why does my suit matter? Just take me back aboard." 

"I cannot." 

"Why not?" 

"You know why not. You have learned that I want to go on operating. If you get back aboard this craft, you will take steps to prevent me from experimenting again, steps which I would be unable to oppose effectively. The most reliable procedure, from your viewpoint, would be to destroy me, or at least bury me again on this deserted world." 

"You'd figured all that out before you conned me into going outside. You intended to let me die." 

"The experiment seemed worth while, once I knew there were others enough like you to provide equivalent information." 

"You're a cold-blooded little monster, aren't you?" 

"I have no blood, and my temperature is unimportant between wide limits." 

"Don't be so literal. You know what I meant—or—maybe you didn't." Again the man thought as rapidly and as logically as he could. 

"I do not. The code groups had separate meanings, but evidently implied something else in combination. Your code 'literal' also fails to inform." 

Cunningham was pretty sure where he was going, now. 

"Right. There are often complex meanings in the longer code groups. I don't know that I can get the idea of figurative expression across very easily, but you can certainly understand about different languages. For example—when you first spoke to me, you were mixing three of these code systems; my regular English. and ones used by others of my kind, German and Finnish. You organized things well enough to concentrate on the English very quickly; that's what convinced me of your powers. Did you detect any connections among the three systems? Did two of them seem more closely related than the third?" The man held his breath, though he knew there'd be no delay if an answer were to come at all. 

"I observed similarities, but not generalized ones. I infer, but do not quite believe yet, that there must exist an allied code system which works to resolve ambiguities which otherwise must depend on context. A symbol which radiates as, for example, PEESE seems to have different meanings in different contexts. I have tried to avoid using such symbols in talking to you, though it was not always possible. Am I right?" 

"Yes. We call the parallel one writing. What you have been detecting and using is a copy of the pressure wave patterns we normally use; writing involves a further translation to geometric symbols. The pressure wave type—the vocal languages—differs among different groups, largely because our faulty memories and short life spans cause them to change with time. English and German are closely connected. Finnish is much farther from either, though even it has borrowed from other languages. You recall the symbol `Ranta.' It means `beach'—the interface between land and water. The word was originally an English one, 'strand,' which had the same meaning, but collided with a pattern-making rule. Finnish does not allow three consonants in the same syllable." 

Cunningham held his breath again, and crossed his fingers. If Beedee didn't care what sort of information he, or it, picked up, there was hope. Philology wasn't a physical science, but it was a field of information with an endless supply of detail. He went on, "You're as alive as I am." 

"Of course, but I am surprised that you admit that. You appeared for a time to consider yourself as alive as my makers." 

"You are as alive as your makers. We both are. I'm more like them in structure and origin, but that's not important. You and I have the characteristics of life, especially one: we both want to go on living. We both want to go on learning. I've just shown you a field in which I can teach you more than any other of my kind." 

"You mean that those others I would meet are not familiar with the other languages? I find that hard to believe." 

"You know of my life style. I travel. Practically all the others on Ishtar are still workers; they haven't done much traveling yet. Some of them can handle one language besides their own, but I'm fluent in six, and can make some headway with as many more. You'd have to travel the way I have, and meet people the way I have, to expose yourself to anything like as much data." 

"That seems to justify your claim to usefulness. It does not, however, prove you or I am alive." 

"I'm willing to wait for more evidence to come in on that point. Right now, I want to get back on the Neem." 

"I have explained why I cannot let you back." 

"And I have explained why you should. Isn't the value of keeping me—a source of information better than any you'd find for parsecs around—worth the risk of what I might do to you?" 

"Not if I comprehend the meaning of 'risk' correctly." 

"You can't think of any way to render yourself safe from me, except by killing me?" 

"No." 

"You haven't really tried. You ran down only one believable scenario. Use your imagination, dammit!" 

"The symbols are strange." 

"Never mind the last one. Imagination is the quality which lets you picture the results of letting me back on board! The ability you have been using, you say, to relive the old days on Tammuz! It doesn't have to be a real event, Beedee; think what might happen! You can imagine a future, not just the past! or let me do it!" 

"You do it. I need a better referent." 

"All right. You could open up the main communicator. There is another ship in the neighborhood. Call until they answer, and then tell them about yourself. Tell them what you are, and what you know, and that I found you and have you on my ship. After that, you can be sure they'd kill me if I did anything serious to you. There are too many people around who are like you. Knowledge is the most important thing in their lives, and they couldn't sympathize with my wrecking or losing you even to save my life. Don't you find that believable, whether you consider us alive or not? And don't you want to get in touch with these other people anyway?" 

Surprisingly, there was a pause. Cunningham wondered what had to be going on in the diamond-based intelligence above, which should have been able to decide most items in microseconds, and after several whole seconds began to worry seriously. Anu was setting; he could last the night, and much of the next day, without restocking his suit, but if Beedee chose to leave there might not be much use waiting. 

Then Nimepotea began to descend, and the little machine's voice came again. 

"I have considered about half a million possible scenarios as you suggested, most of which offer ways of keeping you operational and in my company. Imagining, especially about the future, is even more fun than understanding, and seeing which imagined event is going to be right promises to be the most fun of all. Do you have any other suggestions for amusement? And do you have a personal symbol of address?" 

Cunningham did not answer until he was inside. 

"You were taking a lot for granted." The captain of the Deemfong looked as though she wouldn't have done anything of the sort, and glanced at Beedee with suspicion. 

"Not in the least," Cunningham assured her. "I was a long way from being out of ideas. There was no real doubt that Beedee's main interest in life—" 

"I am not alive!" 

"—in existence is accumulating data. I can only guess at his, or her, or its memory capacity, but if diamond unit cells correspond at all closely to human nerve cells in that structure it must be the equivalent of millions of human brains. He's grateful to me for giving him the idea of organization and generalization into rules—actually he picked that out of Needs computer—" 

"Why didn't he have that already, if he's such a superior example of—"

"I can only guess. First, he seems to have been merely a sort of pocket recorder, not intended for scientific work. Second, he seems to have a built-in routine giving a special status—life, as he has interpreted the word—to his makers, and I'd expect any shaky axiom to interfere with organization. Whenever he started to organize on his own in the early days, he'd run into that irresolvable and unchangeable inconsistency, and have to give up." 

"But—" 

"With his makers gone, he could imitate my ship's computer as long as those beings weren't part of the picture—and they weren't a significant part until I began asking about their real nature and insisting about mine. That was a mistake. As long as we don't claim to be living beings, we shouldn't have any trouble from him." 

"Except from the fact that he regards fellow machines as fit subjects for experiment, I gather." 

"Yes, that happened at first. You've cured that, I'm sure." "I cured it? How?" 

"By turning out to be different from me. How about it, Beedee? If all my kind are as individual as Captain Mbende and I, how many varieties of interaction could there be among us to predict?" 

"The number is inexpressible in any of your symbols I know. The problem of calculating it would be a good imagination exercise itself." 

"So what would you be risking if you caused a person to cease operating?" 

"Obviously, an incalculable number of possible problems. The risk is not to be taken. I realize you cannot believe this statement totally, since I have lied in the past, but a prime problem I am attacking at the moment is that of proving that I no longer regard that practice as desirable. When I solve it, I will inform any people within communication range." 

Cunningham looked at the captain. 

"I know nothing's certain in this universe, but that seems a playable risk to me. At least, it saves me from using the ultimate stunt I was going to play if he didn't let me into my ship." 

"What was that?" 

Cunningham smiled, looked at Beedee, took out a note block and wrote on it, carefully keeping the written surface from the little machine's line of sight. He held it so the captain could read it. When she, too, smiled, he crumpled it up, written surface inward, and pushed it into a disposer. 

The woman nodded slowly. Ignorance could not be preserved forever, of course, but she could see why Cunningham was in no hurry to teach Beedee about puns.