"Four miles. Have to crack the valve again."

The ship dropped.

"I can see ground," said Eric.

I couldn't. Eric caught me straining my eyes and said, "Forget it. I'm using deep infrared, and getting no detail."

"No vast, misty swamps with weird, terrifying monsters and man-eating plants?"

"All I see is hot, bare dirt."

But we were almost down, and there were no cracks in the cabin wall. My neck and shoulder muscles loosened. I turned away from the window. Hours had passed while we dropped through the poisoned, thickening air. I already had most of my suit on. Now I screwed on my helmet and three-finger gauntlets.

"Strap down," said Eric. I did.

We bumped gently. The ship tilted a little, swayed back, bumped again. And again, with my teeth rattling and my armor-plated body rolling against the crash webbing. "Damn,"

Eric muttered. I heard the hiss from above. Eric said, "I don't know how we'll get back up."

Neither did I. The ship bumped hard and stayed down, and I got up and went to the airlock.

"Good luck," said Eric. "Don't stay out too long." I waved at his cabin camera. The outside temperature was seven hundred and thirty.

The outer door opened. My suit refrigerating unit set up a complaining whine. With an empty bucket in each hand, and with my headlamp blazing a way through the black murk, I stepped out onto the right wing.

My suit creaked and settled under the pressure, and I stood on the wing and waited for it to stop. It was almost like being under water. My headlamp beam went out thick enough to be solid, penetrating no more than a hundred feet. The air couldn't have been that opaque, no matter how dense. It must have been full of dust, or tiny droplets of some fluid.

The wing ran back like a knife-edged running board, widening toward the tail until it spread into a tailfin. The two tailfins met back of the fuselage. At the tailfin tip was the ram, a big sculptured cylinder with an atomic engine inside. It wouldn't be hot because it hadn't been used yet, but I had my counter anyway.

I fastened a line to the wing and slid to the ground. As long as we were here... The ground turned out to be a dry, reddish dirt, crumbly, and so porous that it was almost spongy. Lava etched by chemicals? Almost anything would be corrosive at this pressure and temperature. I scooped one pailful from the surface and another from underneath the first, then climbed up the line and left the buckets on the wing.

The wing was terribly slippery. I had to wear magnetic sandals to stay on. I walked up and back along the two hundred foot length of the ship, making a casual inspection. Neither wing nor fuselage showed damage. Why not? If a meteor or something had cut Eric's contact with his sensors in the rams, there should have been evidence of a break in the surface.

Then, almost suddenly, I realized that there was an alternative.

It was too vague a suspicion to put into words yet, and I still had to finish the inspection. Telling Eric would be very difficult if I was right.

Four inspection panels were set into the wing, well protected from the reentry heat. One was halfway back on the fuselage, below the lower edge of the blimp tank, which was molded to the fuselage in such a way that from the front the ship looked like a dolphin. Two more were in the trailing edge of the tailfin, and the fourth was in the ram itself. All opened, with powered screwdriver on recessed screws, on junctions of the ship's electrical system.

There was nothing out of place under any of the panels. By making and breaking contacts and getting Eric's reactions, I found that his sensation ended somewhere between the second and third inspection panels. It was the same story on the left wing. No external damage, nothing wrong at the junctions. I climbed back to ground and walked slowly beneath the length of each wing, my headlamp tilted up. No damage underneath.

I collected my buckets and went back inside.

"A bone to pick?" Eric was puzzled. "Isn't this a strange time to start an argument? Save it for space. We'll have four months with nothing else to do."

"This can't wait. First of all, did you notice anything I didn't?" He'd been watching everything I saw and did through the peeper in my helmet.

"No. I'd have yelled."

"Okay. Now get this.

"The break in your circuits isn't inside, because you get sensation up to the second wing inspection panels. It isn't outside because there's no evidence of damage, not even corrosion spots. "That leaves only one place for the flaw."

"Go on."

"We also have the puzzle of why you're paralyzed in both rams. Why should they both go wrong at the same time?

There's only one place in the ship where the circuits join."

"What? Oh, yes, I see. They join through me."

"Now let's assume for the moment that you're the piece with the flaw in it. You're not a piece of machinery, Eric. If something's wrong with you it isn't medical. That was the first thing we covered. But it could be psychological."

"It's nice to know you think I'm human. So I've slipped a cam, have I?"

"Slightly. I think you've got a case of what used to be called trigger anaesthesia. A soldier who kills too often sometimes finds that his right index finger or even his whole hand has gone numb, as if it were no longer a part of him. Your comment about not being a machine is important, Eric. I think that's the whole problem. You've never really believed that any part of the ship is a part of you. That's intelligent, because it's true. Every time the ship is redesigned you get a new set of parts, and it's right to avoid thinking of a change of model as a series of amputations."

I'd been rehearsing this speech, trying to put it so that Eric would have no choice but to believe me. Now I know that it must have sounded phony. "But now you've gone too far.

Subconsciously you've stopped believing that the rams can feel like a part of you, which they were designed to do. So you've persuaded yourself that you don't feel anything."

With my prepared speech done, and nothing left to say, I stopped talking and waited for the explosion.

"You make good sense," said Eric.

I was staggered. "You agree?"

"I didn't say that. You spin an elegant theory, but I want time to think about it. What do we do if it's true?"

"Why... I don't know. You'll just have to cure yourself."

"Okay. Now here's my idea. I propose that you thought up this theory to relieve yourself of a responsibility for getting us home alive. It puts the whole problem in my lap, metaphorically speaking."

"Oh, for-"

"Shut up. I haven't said you're wrong. That would be an ad hominem argument. We need time to think about this."

It was lights-out, four hours later, before Eric would return to the subject.

"Howie, do me a favor. Assume for awhile that something mechanical is causing all our trouble. I'll assume it's psychosomatic."

"Seems reasonable."

"It is reasonable. What can you do if I've gone psychosomatic? What can I do if it's mechanical? I can't go around inspecting myself. We'd each better stick to what we know."

"It's a deal." I turned him off for the night and went to bed.

But not to sleep.

With the lights off it was just like outside. I turned them back on. It wouldn't wake Eric. Eric never sleeps normally, since his blood doesn't accumulate fatigue poisons, and he'd go mad from being awake all the time if he didn't have a Russian sleep inducer plate near his cortex. The ship could implode without waking Eric when his sleep inducer's on. But I felt foolish being afraid of the dark.

While the dark stayed outside it was all right.

But it wouldn't stay there. It had invaded my partner's mind.

Because his chemical checks guard him against chemical insanities like schizophrenia, we'd assumed he was permanently sane. But how could any prosthetic device protect him from his own imagination, his own misplaced common sense?