"You're a very lucky man," I said.

"No doubt. What is that?"

Black and furry, an inch and a half long; one end wiggling in blind curiosity as it moved along the bark.

"A caterpillar. You know, there's no computing the odds you ran against being alive now. You don't seem very cheerful about it."

"I was... but think about it," said the rammer. "Think what the intruder must have reasoned out, to do what he did.

"He looked through the main window to examine me as well as he could. I was tied to a chair by crash straps, and his sensors had to see through thick impact quartz designed for transparency in the other direction. He could see me, but only from the front. He could examine the ship, but it was damaged, and he had to guess to what extent.

"First he must have reasoned that I could not slow my ship without the ramscoop web. But he must also have deduced the presence of reserve fuel to decelerate me to zero speed from the lowest speed at which my ramscoop can operate. It is apparent that I must have it. Thus he stopped me dead, or nearly so, and left me to go home the slow way, using only my re-entry reserve fuel.

"After he had left me, he must have realized that I would be dead of age before I ended such a trip. Imagine how thorough his examination of me must have been! So he came back for me.

"By projecting my line of flight he must have known where I was going. But could I live there with a damaged ship? He did not know.

"And so he looked me over more carefully, deduced the star and planet where I must have evolved, and he put me there."

"That's pretty farfetched," I said.

"Yes! The solar system was twelve light-years distant, yet he reached it in an instant! But that is not the point... ." The rammer let his voice trail off. He seemed oddly fascinated by the black caterpillar, which was now defying gravity as it explored a vertical wall of bark. "He placed me not only on Earth, but in North Africa. He deduced not only my planet of origin, but the region where I had evolved.

"I stayed in my pod for two hours before I was found. Your United Nations police took a record of my mind, but they do not believe what they found. A ramship pod cannot be towed to Earth without radar finding it. Further, my ramscoop web is all over the desert. Even the hydrogen balloons survived the reentry. They think that it must be a hoax, that I was brainwashed as part of that hoax."

"And you? What do you think?"

Again the rammer's face tightened into jigsaw-puzzle lines. "I had convinced myself that the intruder was no more than another spacecraft pilot—a passerby who stopped to help, as some persons will stop to help if your car battery fails far from a city. His power might be greater than mine. He might be wealthier, even within the context of his own culture. We were of different species. Yet he had stopped to help a member of the great brotherhood, for we were both spacemen."

"Because your modern xenology says he couldn't have been your superior."

He didn't answer.

"I can pick a few holes in that theory."

"Can you?"

I ignored his disinterest. "You claim that evolution stops when a species starts building tools. But suppose two tool-users evolved on the same world? Then evolution might go on until one race was dead. We might have had real problems if the dolphins had had hands."

"It may be." He was still watching the caterpillar: an inch and a half of black fur exploring the dark bark. My ear brushed the bark as I faced him, and I smelled the damp wood.

"Then again, not all human beings are alike. There are Einsteins and there are morons. Your passerby might have been of a race that varies more. Make him a super-Einstein—"

"I had not thought of that. I had assumed that his deductions were made with the aid of a computer. At first."

"Then, a species could evolve itself. if they once started fiddling with their genes, they might not stop until their children were mile-high giants with a space drive stuck up their spines. What the hell is so interesting about the caterpillar?"

"You did not see what the boy did?"

"Boy? Oh. No, I didn't."

"There was a... caterpillar moving along the gravel walk. People passed. None looked down. The boy came, and he stooped to watch."

"Oh!"

"Presently the boy picked up the caterpillar, looked about him, then came here and put the caterpillar safely on the limb."

"And you fainted."

"I should not have been so affected by what, after all, is no more than a comparison. I would have cracked my skull had you not caught me."

"A poor return for the golden one, if you had."

The rammer did not smile. "Tell me... if an adult had seen the caterpillar, instead of a boy—"

"Probably he'd have stepped on it."

"Yes, I thought so." The rammer put his tongue in his cheek, which stretched incredibly. "He is nearly upside down. I hope he will not fall off."

"It won't."

"Do you think he is safe there?"

"Sure. Don't worry about it."

The bar was selling a lot of Irish coffee that night. I'd bought two myself. It was warm inside, almost too warm, except when someone pushed through the door. Then a puff of chill, damp fog would roll in.

Beyond the window was grey chaos. The fog picked up all the various city lights: yellow light leaking from inside the bar, passing automobile headlights, white light from frosted street globes, and the rainbow colors of neon signs. The fog stirred all the lights together into a cold graywhite paste and leaked it hack through the windows.

Bright spots drifted past at a pedestrian's pace. Cars. I felt sorry for the drivers. Rolling through a gray formless limbo, running from street globe to invisible street globe, alert for the abrupt, dangerous red dot of a traffic light: an intersection; you couldn't tell otherwise... I had friends in San Francisco; there were other places I could be. But it wasn't my city, and I was damned if I'd drive tonight.

A lost night. I'd finished my drink. One more, and I'd cross the street to my hotel.

"You'd best wait until the fog thins out," said the man next to me.

He was a stranger, medium all over; medium height and weight, regular features, manicured nails, feathery brown hair, no scars. The invisible man. I'd never have looked his way if he hadn't spoken. But he was smiling as if he knew me.

I said, "Sorry?"

"The point is, your hotel might not be there when you've crossed the street. Don't be surprised," he added. "I can read minds. We've learned the knack, where I come from."

There are easy ways to interrupt a conversation with a stranger. A blank stare will do it. But I was bored and alone, and a wacky conversation might be just what I needed.

I said, "Why shouldn't my hotel be exactly where I left it?"

He frowned into his scotch-and-soda, then took a swallow. "Do you know the theory of multiple world lines? It seems that whenever a decision is made, it's made both ways. The world becomes two or more worlds, one for each way the decision can go. Ah, I see you know of it. Well, sometimes the world lines merge again."

‘‘But—''

"That's exactly right. The world must split on the order of a trillion times a second. What's so unbelievable about that? If you want a real laugh, ask a physicist about furcoated particles."

"But you're saying it's real. Every time I get a haircut—"

"One of you waits until tomorrow," said the brown-haired man. "One of you keeps the sideburns. One gets a manicure, one cuts his own nails. The size of the tip varies too. Each of you is as real as the next, and each belongs to a different world line. It wouldn't matter if the world lines didn't merge every so often."