"The purpose of a contemplated human action is always the attainment of a desired subjective experience. But a subjective experience is desired both in terms of intensity and of duration. For an individual the temptingness of different degrees of intensity—of experience is readily computed. However, the temptingness of different durations is equally necessary for an estimate of the probability of a given person performing a given action. This modification depends on the individual's time sense; its acuity and its accuracy. Measurements of time sense . . ."
Probability and Human Conduct—Fitzgerald
Eventually Calhoun left the ship and found a cultivated field and a dead man and other things. But while in the Med Ship he found only bewilderment. The first morning he carefully monitored the entire communications spectrum. There were no man-made signals in the air of Maris III. That was proof the world was uninhabited. But the ship's external microphones picked up a rocket roar in mid-morning. Calhoun looked, and saw the faint white trail of the rocket against the blue of the sky. The fact that he saw it was proof that it was in atmosphere. And that was evidence that the rocket was taking photographs for signs of the crater the Med Ship should have made in a crash landing.
The fact of search was proof that the planet was inhabited, but the silence of the radio spectrum said that it wasn't. The absence of traffic in the city said that it was dead or empty, but there were people there because they'd answered Calhoun's hail, and tried to kill him when he identified himself. But nobody would want to destroy a Med Ship except to prevent a health inspection unless there was a situation aground that the Med Service ought to know about. But there should not be such a situation.
There was no logical explanation for such a series of contradictions. Civilized men acted either this way or that. There could only be civilized men here, yet they acted neither this way nor that. Therefore—and the confusion began all over again.
Calhoun dictated an account of events into the emergency responder in the ship. If a search call came from space, the responder would broadcast this data and Calhoun's intended action. He carefully shut off all other operating circuits so the ship couldn't be found by their radiation. He equipped himself for travel, and he and Murgatroyd left the ship. Obviously, he headed toward the city where whatever was wrong was centered.
Travel on foot was unaccustomed, but not difficult. The vegetation was semi-familiar. Maris III was an Earth-type planet and circled a Sol-type sun, and given similar conditions of gravity, air, sunlight, and temperature range, similar organisms should develop. There would be room, for example, for low-growing ground-cover plants, and there would also be advantages to height. There would be some equivalent of grass, and there would be the equivalent of trees, with intermediate forms having in-between habits of growth. Similar reasoning would apply to animal life. There would be parallel ecological niches for animals to fill, and animals would adapt to fill them.
Maris III was not, then, an "unearthly" environment. It was much more like an unfamiliar part of a known planet than a new world altogether. But there were some oddities. An herbivorous creature without legs which squirmed like a snake. A pigeon-sized creature whose wings were modified, gossamer-thin scales with iridescent colorings. There were creatures which seemed to live in lunatic association, and Calhoun was irritably curious to know if they were really symbiotes or only unrecognizable forms of the same organism, like the terrestrial male and female firefly-glowworm.
But he was heading for the city. He couldn't spare time to biologize. On his first day's journey he looked for food to save the rations he carried. Murgatroyd was handy here. The little tormal had his place in human society. He was friendly, and he was passionately imitative of human beings, and he had a definite psychology of his own. But he was useful, too. When Calhoun strode through the forests, Murgatroyd strode grandly with him, imitating his walk. From time to time he dropped to all four paws to investigate something. He invariably caught up with Calhoun within seconds.
Once Calhoun saw him interestedly bite a tiny bit out of a most unpromising-looking shrub stalk. He savored its flavor, and then swallowed it. Calhoun took note of the plant and cut off a section. He bound it to the skin of his arm up near the elbow. Hours later there was no allergic reaction, so he tasted it. It was almost familiar. It had the flavor of a bracken shoot, mingled with a fruity taste. It would be a green bulk food like spinach or asparagus, filling but without much substance.
Later, Murgatroyd carefully examined a luscious-seeming fruit which grew low enough for him to pluck. He sniffed it closely and drew back. Calhoun noted that plant, too. Murgatroyd's tribe was bred at headquarters for some highly valuable qualities. One was a very sensitive stomach—but it was only one. Murgatroyd's metabolism was very close to man's. If he ate something and it didn't disagree with him, it was very likely safe for a man to eat it too. If he rejected something, it probably wasn't. But his real value was much more important than the tasting of questionable foods.
When Calhoun camped the first night, he made a fire of a plant shaped like a cactus barrel and permeated with oil. By heaping dirt around it, he confined its burning to a round space very much like the direct-heat element of an electronic stove. It was an odd illustration of the fact that human progress does not involve anything really new in kind, but only increased convenience and availability of highly primitive comforts. By the light of that circular bonfire, Calhoun actually read a little. But the light was inadequate. Presently he yawned. One did not get very far in the Med Service without knowing probability in human conduct. It enabled one to check on the accuracy of statements made, whether by patients or officials, to a Med Ship man. Today, though, he'd traveled a long way on foot. He glanced at Murgatroyd, who was gravely pretending to read from a singularly straight-edged leaf.
"Murgatroyd," said Calhoun, "it is likely that you will interpret any strange sound as a possible undesirable subjective experience. Which is to say, as dangerous. So if you hear anything sizable coming close during the night, I hope you'll squeal. Thank you."
Murgatroyd said, "Chee," and Calhoun rolled over and went to sleep.
It was mid-morning of the next day when he came upon a cultivated field. It had been cleared and planted, of course, in preparation for the colonists who'd been expected to occupy the city. Familiar Earth plants grew in it, ten feet high and more. And Calhoun examined it carefully, in the hope of finding how long since it had received attention. In this examination, he found the dead man.
As a corpse, the man was brand new, and Calhoun very carefully put himself into a strictly medical frame of mind before he bent over for a technical estimate of what had happened, and when. The dead man seemed to have died of hunger. He was terribly emaciated, and he didn't belong in a cultivated field far from the city. By his garments he was a city dweller and a prosperous one. He wore the jewels which nowadays indicated a man's profession and status much more than the value of his possessions. There was money in his pockets, and writing materials, a wallet with pictures and identification, and the normal oddments a man would carry. He'd been a civil servant of the city. And he shouldn't have died of starvation.
He especially shouldn't have gone hungry here! The sweet maize plants were tall and green. Their ears were ripe. He hadn't gone hungry! There were the inedible remains of at least two dozen sweet maize ears. They had been eaten some time—some days—ago, and one had been left unfinished. If the dead man had eaten them but was unable to digest them, his belly should have been swollen with undigested food. It wasn't. He'd eaten and digested and still had died, at least largely of inanition.
Calhoun scowled.
"How about this corn, Murgatroyd?" he demanded.
He reached up and broke off a half-yard-long ear. He stripped away the protecting, stringy leaves. The soft grains underneath looked appetizing. They smelled like good fresh food. Calhoun offered the ear to Murgatroyd.
The little tormal took it in his paws and on the instant was eating it with gusto.
"If you keep it down, he didn't die of eating it," said Calhoun, frowning. "And if he ate it—which he did—he didn't die of starvation. Which he did."
He waited. Murgatroyd consumed every grain upon the oversized cob. His furry belly distended a little. Calhoun offered him a second ear. He set to work on that, too, with self-evident enjoyment.
"In all history," said Calhoun, "nobody's ever been able to poison one of you tormals because your digestive system has a qualitative analysis unit in it that yells bloody murder if anything's likely to disagree with you. As a probability of tormal reaction, you'd have been nauseated before now if that stuff wasn't good to eat."
But Murgatroyd ate until he was distinctly pot-bellied. He left a few grains on the second ear with obvious regret. He put it down carefully on the ground. He shifted his left-hand whiskers with his paw and elaborately licked them clean. He did the same to the whiskers on the right-hand side of his mouth. He said comfortably, "Chee!"
"Then that's that," Calhoun told him. "This man didn't die of starvation. I'm getting queasy!"
He had his lab kit in his shoulder pack, of course. It was an absurdly small outfit, with almost microscopic instruments. But in Med Ship field work the techniques of microanalysis were standard. Distastefully, Calhoun took the tiny tissue sample from which he could gather necessary information. Standing, he ran through the analytic process that seemed called for. When he finished, he buried the dead man as well as he could and started off in the direction of the city again. He scowled as he walked.
He journeyed for nearly half an hour before he spoke. Murgatroyd accompanied him on all fours now because of his heavy meal. After a mile and a half, Calhoun stopped and said grimly, "Let's check you over, Murgatroyd."
He verified the tormal's pulse and respiration and temperature. He put a tiny breath sample through the part of the lab kit which read off a basic metabolism process. He submitted blandly. The result of the checkover was that Murgatroyd the tormal was perfectly normal.
"But," said Calhoun angrily, "that man died of starvation! There was practically no fat in the tissue sample at all! He arrived where we found him while he was strong enough to eat, and he stayed where there was good food, and he ate it, and he digested it, and he died of starvation: Why?"
Murgatroyd wriggled unhappily, because Calhoun's tone was accusing. He said, "Chee!" in a subdued tone of voice. He looked pleadingly up at Calhoun.
"I'm not angry with you," Calhoun told him, "but dammit—"
He packed the lab kit back into his pack, which contained food for the two of them for about a week.
"Come along!" he said bitterly. He started off. Ten minutes later he stopped. "What I said was impossible. But it happened, so it mustn't have been what I said. I must have stated it wrongly. He could eat, because he did. He did eat, because of the cobs left. He did digest it. So why did he die of starvation? Did he stop eating?"
"Chee!" said Murgatroyd with conviction.
Calhoun grunted and marched on once more. The man had not died of a disease, not directly. The tissue analysis gave a picture of death which denied that it came of any organ ceasing to function. Was it the failure of the organism—the man—to take the action required for living? Had he stopped eating?
Calhoun's mind skirted the notion warily. It was not plausible. The man had been able to feed himself and had done so. Anything which came upon him and made him unable to feed himself . . .
"He was a city man," growled Calhoun, "and this is a damned long way from the city. What was he doing out here, anyhow?"
He hesitated and tramped on again. A city man found starved in a remote place might have become lost, somehow or other. But if this man was lost, he was assuredly not without food.
"He belonged in the city," said Calhoun vexedly, "and he left it. The city's almost but not quite empty. Our would-be murderers are in it. This is a new colony. There was a city to be built and fields to be plowed and planted, and then a population was to come here from Dettra Two. The city's built and the fields are plowed and planted. Where's the population?"
He scowled thoughtfully at the ground before him. Murgatroyd tried to scowl too, but he wasn't very successful.
"What's the answer, Murgatroyd? Did the man come away from the city because he had a disease? Was he driven out?"
"Chee," said Murgatroyd without conviction.
"I don't know either," admitted Calhoun. "He walked out into the middle of that field and then stopped walking. He was hungry and he ate. He digested. He stayed there for days. Why? Was he waiting to die of something? Presently he stopped eating. He died. What made him leave the city? What made him stop eating? Why did he die?"
Murgatroyd investigated a small plant and decided that it was not interesting. He came back to Calhoun.
"He wasn't killed," said Calhoun, "but somebody tried to kill us—somebody who's in the city now. That man could have come out here to keep from being killed by the same people. Yet he died anyhow. Why'd they want to kill him? Why'd they want to kill us? Because we were a Med Ship? Because they didn't want Med Service to know there was a disease here? Ridiculous!"
"Chee," said Murgatroyd.
"I don't like the looks of things," said Calhoun. "For instance, in any ecological system there are always carrion eaters. At least some of them fly. There would be plain signs if the city was full of corpses. There aren't any. On the other hand, if the city was inhabited, and there was sickness, they would welcome a Med Ship with open arms. But that dead man didn't come away from the city in any ordinary course of events, and he didn't die in any conventional fashion. There's an empty city and an improbable dead man and a still more improbable attempt at murder! What gives, Murgatroyd?"
Murgatroyd took hold of Calhoun's hand and tugged at it. He was bored. Calhoun moved on slowly.
"Paradoxes don't turn up in nature," said Calhoun darkly. "Things that happen naturally never contradict each other. You only get such things when men try to do things that don't fit together—like having a plague and trying to destroy a Med Ship, if that's the case, and living in a city and not showing on its streets, if that is occurring, and dying of starvation while one's digestion is good and there's food within hand's reach. And that did happen! There was dirty work at the spaceport, Murgatroyd. I suspect dirty work at every crossroad. Keep your eyes open."
"Chee," said Murgatroyd. Calhoun was fully in motion, now, and Murgatroyd let go of his hand and went on ahead to look things over.
Calhoun crossed the top of a rounded hillcrest some three miles from the shallow grave he'd made. He began to accept the idea that the dead man had stopped eating for some reason, as the only possible explanation of his death. But that didn't make it plausible. He saw another ridge of hills ahead.
In another hour he came to the crest of that farther range. It was the worn-down remnant of a very ancient mountain chain, now eroded to a mere fifteen hundred or two thousand feet. He stopped at the very top. Here was a time and place to look and take note of what he saw. The ground stretched away in gently rolling fashion for very many miles, and there was the blue blink of sea at the horizon. A little to the left he saw shining white. He grunted.
That was the city of Maris III, which had been built to receive colonists from Dettra and relieve the population pressure there. It had been planned as the nucleus of a splendid, spacious, civilized world-nation to be added to the number of human-occupied worlds. From its beginning it should have held a population in the hundreds of thousands. It was surrounded by cultivated fields, and the air above it should have been a-shimmer with flying things belonging to its inhabitants.
Calhoun stared at it through his binoculars. They could not make an image, even so near, to compare with that which the electron telescope had made from space, but he could see much. The city was perfect. It was intact. It was new. But there was no sign of occupancy anywhere. It did not look dead, so much as frozen. There were no fliers above it. There was no motion on the highways. He saw one straight road which ran directly away along his line of sight. Had there been vehicles on it, he would have seen at least shifting patches of color as clots of traffic moved together. There were none.
He pressed his lips together and began to inspect the nearer terrain. He saw foreshortened areas where square miles of ground had been cleared and planted with Earth vegetation. This was a complicated process. First the ground had to be bulldozed clean, and then great sterilizers had to lumber back and forth, killing every native seed and root and even the native soil bacteria. Then the land had to be sprayed with cultures of the nitrogen-fixing and phosphorous-releasing microscopic organisms which normally live in symbiosis with Earth plants. These had to be tested beforehand for their ability to compete with indigenous bacterial life. And then Earth plants could be sown.
They had been. Calhoun saw that inimitable green which a man somehow always recognizes. It is the green of plants whose ancestors thrived on Earth and which have followed that old planet's children halfway across the galaxy.
"There's a look to a well-tended field," said Calhoun, after a long look through binoculars, "that shows what kind of people cultivated it. There are fields up ahead that are well laid out, but nobody's touched them for weeks. The furrows are straight and the crops healthy. But they're beginning to show neglect. If the city was finished and waiting for its population, there would be caretakers tending the fields until the people came. There's been no caretaking done here!"
Murgatroyd stared wisely about as he considered Calhoun to be doing.
"In short," said Calhoun, "something's happened that I don't like. The population must be nearly zero or the fields would have been kept right. One man can keep a hell of a lot of ground in good shape, with modern machinery. People don't plant fields with the intention to neglect them. There's been a considerable change of plans around here. Enmity to a Med Ship is something more than a random impulse." Calhoun was not pleased. With the vision screens of his ship burned out, a return to headquarters was out of the question. "Whoever was handling the landing grid doesn't want help. He doesn't even want visitors. But Med Service was notified to come and look over the new colony. Either somebody changed his views drastically, or the people in charge of the landing grid aren't the ones who asked for a public health checkup."
Murgatroyd said profoundly, "Chee!"
"The poor devil I buried even seems to hint at something of the sort. He could have used help! Maybe there are two kinds of people here. One kind doesn't want aid and tried to kill us because we'd offer it. The other kind needs it. If so, there might be a certain antagonism . . ."
He stared with knitted brows over the vast expanse toward the horizon. Murgatroyd, at this moment, was a little way behind Calhoun. He stood up on his hind legs and stared intently off to one side. He shaded his eyes with a forepaw in a singularly humanlike fashion and looked inquisitively at something he saw. Calhoun did not notice.
"Make a guess, Murgatroyd," he commanded. "Make a wild one. A dead man who'd no reason for dying. Live people who should have no reason for wanting to spatter us against the walls of our Med Ship. Something was fatal to that dead man. Somebody tried to be fatal to us. Is there a connection?"
Murgatroyd stared absorbedly at a patch of brushwood some fifty yards to his left. Calhoun started down the hillside. Murgatroyd remained fixed in a pose of intensely curious attention to the patch of brush. Calhoun went on. His back was toward the brush thicket.
There was a deep-toned, musical twanging sound from the thicket. Calhoun's body jerked violently from an impact. He stumbled and went down, with the shaft of a wooden projectile sticking out of his back. He lay still.
Murgatroyd whimpered. He rushed to where Calhoun lay upon the ground. He danced in agitation, chattering shrilly. He wrung his paws in humanlike distress. He tugged at Calhoun, but Calhoun made no response.
A girl emerged from the thicket. She was gaunt and thin, yet her garments had once been of admirable quality. She carried a strange and utterly primitive weapon. She moved toward Calhoun, bent over him and laid a hand to the wooden projectile she had fired into his back.
He moved suddenly. He grappled. The girl toppled, and he swarmed upon her savagely as she struggled. But she was taken by surprise. There was the sound of panting, and Murgatroyd danced in a fever of anxiety.
Then Calhoun stood up quickly. He stared down at the emaciated girl who had tried to murder him from ambush. She was panting horribly now.
"Really," said Calhoun in a professional tone, "as a doctor I'd say that you should be in bed instead of wandering around trying to murder total strangers. When did this trouble begin? I'm going to take your temperature and your pulse. Murgatroyd and I have been hoping to find someone like you. The only other human being I've met on this planet wasn't able to talk."
He swung his shoulder pack around and impatiently jerked a sharp-pointed stick out of it. It was the missile, which had been stopped by the pack. He brought out his lab kit. With absolute absorption in the task, he prepared to make a swift check of his would-be murderer's state of health.
It was not good. There was already marked emaciation. The desperately panting girl's eyes were deep-sunk, hollow. She gasped and gasped. Still gasping, she lapsed into unconsciousness.
"Here," said Calhoun curtly, "you enter the picture, Murgatroyd. This is the sort of thing you're designed to handle."
He set to work briskly. Presently he observed, "Besides a delicate digestion and a hair-trigger antibody system, Murgatroyd, you ought to have the instincts of a watchdog. I don't like coming that close to being shot by a lady patient. See if there's anybody else around, will you?"
"Chee," said Murgatroyd shrilly. But he didn't understand. He watched as Calhoun deftly drew a small sample of blood from the unconscious girl's arm and painstakingly put half the tiny quantity into an almost microscopic ampule in the lab kit. Then he moved toward Murgatroyd. The tormal wriggled as Calhoun made the injection. But it did not hurt. There was an insensitive spot on his flank where the nerves had been blocked off before he was a week old.
"As one medical man to another," said Calhoun, "you've noticed that the symptoms are of anoxia—oxygen starvation. Which doesn't make sense in the open air where we're breathing comfortably. Another paradox, Murgatroyd! But there's an emergency, too. How can you relieve anoxia when you haven't any oxygen?"
He looked down at the unconscious girl. She displayed the same sort of emaciation he'd noted in the dead man in the field some miles back. Patients with a given disease often acquire a certain odd resemblance to each other. This girl seemed to be in an earlier stage of whatever had killed the civil servant in the corn field. He'd died of starvation with partly eaten food by his hand. She'd tried to murder Calhoun, just as persons unknown, in the city, had tried to kill both Calhoun and Murgatroyd in the Med Ship some forty thousand miles out in space. But her equipment for murder was not on a par with that of the operators of the landing grid. She didn't belong in their class. She might be a fugitive from them.
Calhoun put these things together. Then he swore in sudden bitter anger. He stopped abruptly, in concern lest she'd heard.
She hadn't. She was still insensible.