Kaliinin was listening gravely. She said, "Can you imagine why no one can duplicate your work?"

"The easiest explanation is that there is something wrong with me, that I am a crank - if not a madman. I believe that some of my colleagues suspect that to be the answer."

"Do you think you're a madman?"

"No, I don't, Sophia, but even I waver sometimes. You see, after you isolate the skeptic waves and amplify them, it is conceivable that the human brain itself might become a receiving instrument. The waves may transfer the thoughts from the thinker you are studying directly to you. The brain would certainly be an extraordinarily delicate receiver, but it would also be an extraordinarily individual one. If I improved my program so that I could sense the thoughts better, that would mean I improved it to suit my own individual brain. Other brains might not be affected and, in fact, might be less affected, the closer I adjusted it to mine. It would be like a painting. The closer a painting is made to look like me, the less it looks like anyone else. The more I can make my program produce sensible self-consistent results, the less anyone else can."

"Have you actually sensed thought?"

"I'm not sure. There are times I have thought I did, but I'm never quite convinced it's not my imagination. Certainly no one else - with my program or any other - has sensed anything. I have used the twinkle to track down the skeptic nodes in the brains of chimpanzees and from that reasoned out where they would be in human brains, but that is not accepted either. It is considered the overenthusiasm of a scientist oversold on his own unlikely theory. And even using leads into the skeptic nodes - on animals, of course - I couldn't be sure."

"With animals it would be difficult. Have you published these - sensations of yours?"

"I haven't dared," said Morrison, shaking his head. "No one would accept such subjective findings. I've mentioned it in passing to several people - foolish of me - and the news spread and merely convinced my colleagues all the more firmly that I am, shall we say, unstable. It was only last Sunday that Natalya told me that Shapirov took me seriously, but he is considered, at least in my country, to be unstable, too."

"He is not," said Kaliinin firmly, "or was not."

"It would be nice to think he wasn't, obviously."

Konev, from in front of Morrison, said suddenly, without turning around, "It was your sensations of thought that impressed Shapirov. I know! He discussed it with me. He said on a number of occasions that your program was a relay station and he would like to try it himself. If you were inside a neuron, a key neuron of the skeptic node, things would be different. You would sense thoughts unmistakably. Shapirov thought so and I think so. Shapirov thought it possible you might even have sensed thoughts unmistakably as it was, but were not ready to let the world know. Is that so?"

How they harped on secrecy, all of them, thought Morrison. Then he caught the look on Kaliinin's face. Her mouth was partly open, her eyebrows drawn together, her finger hovering near her lips. It was as though she wanted to ask him to be quiet with a kind of agonizing intensity, without quite daring to do so openly.

But then he was distracted by Dezhnev's voice, joyfully loud. "Enough babble, my children. The Grotto has located us and we are, to their enormous astonishment, exactly where we say we are."

Konev threw up both hands and his voice sounded almost boyish. "Exactly where I say we are."

Dezhnev said, "Let us have communal responsibility. Where we say we are."

"No," said Boranova. "I ordered Konev to make the decision on his own responsibility. The credit is therefore his."

Konev was not mollified. He said, "You would not have so quickly demanded communal responsibility, Arkady Vissarionovich" - he used the patronymic in a style long out of fashion in the Soviet Union, as though to emphasize the fact that Dezhnev was the son of a peasant, among whom, only, the style remained in fashion - "had we proved to be in the wrong capillary."

Dezhnev's smile became an uncomfortable one and his somewhat yellow upper incisors caught at his lower lip.

Boranova said in her masterful contralto, cutting off any retort Dezhnev might have made, "And Shapirov. What of him?"

"That," said Dezhnev, "has passed. An injection of some sort steadied the heartbeat."

Konev said, "Well, then, are we ready to go?"

"Yes," said Boranova.

"In that case - out of the bloodstream at last."

Boranova and Kaliinin were bent over their instruments. Morrison watched them for a few moments, but, of course, knew nothing of what was going on. He turned to Dezhnev, who sat in a relaxed position (unlike Konev, whose body was tense, almost ridged with muscle), and said, "What will be done, Arkady? We can't very well just blast our way out of a blood vessel in the brain."

"We'll sneak out once we're small enough. We're miniaturizing again. Look around you."

Startled, Morrison did. He realized that every time the outside world seemed to stabilize, he quickly learned to take it for granted and to pay no attention to it.

The current had picked up speed. Or, rather, it hadn't, but the ship had shrunk in size once more and objects moving by took correspondingly less time to pass, so that the mind, insisting on considering the ship's size unchanged, interpreted what was seen as a faster current.

A red cell passed by, moving as it had (or seeming to move as it had) in the carotid artery, but despite its speed, it billowed past for a long time, like a quivering whale passing a rowboat. It had grown faint indeed. It was almost transparent now and its edge was fuzzy with Brownian motion. There was a grayish dimness about it, so that it looked like an angry thundercloud spreading its way over the heavens. It had lost most of its oxygen by this time, of course, giving it up to the avid brain cells which, without motion or visible signs of life, consumed one quarter of all the oxygen carried by the blood to the various organs of the body. For all that the brain seemed to simply sit there, sense perception, response, and thought, all of it coordinated with a complexity that no human computer could come within an astronomical distance of duplication - might never duplicate - did not come cheap.

To make up for the spreading of the red cells, the platelets, and the comparatively rare white cells that had grown into monsters that were now too large to grasp, the blood plasma was becoming far less featurelessly liquid.

It had started to turn grainy and now the grains were slowly expanding as they shot past with gradually increasing speed. Morrison knew he was looking at protein molecules and, after a while, it seemed to him that through their whirling and flexing he could make out the helical arrangements of their atoms in fuzzy manner. Some had a miniature forest of lipid molecules partially encasing them.

He was becoming aware also of movement, not the tremble of Brownian motion but a lurching that was becoming more pronounced.

He turned his head to look out the other side at the capillary wall to which they were attached.

The tiling was gone - or at least one tile (or cell, as he might as well think of it now) had expanded to the point where it was the only one to be seen. Slipping off behind was the bulge of the nucleus of the cell, large and thick and growing larger and thicker.

The ship lurched as part of it slid away from the wall and then lurched again as it slid back.

"What's happening?" said Morrison, looking at Kaliinin, who shook her head impatiently. She was totally absorbed in her work.

Dezhnev said, "Sophia is trying to neutralize the ship's electric charge here and there so that it lets go before the tension damages the wall. And she has to find new areas of attachment to keep from losing the wall altogether. It's not easy, having to miniaturize and, at the same time, staying attached to the wall."