"The first two or three hours of that dead man's float is a good test for basketball duty, Barton. It's a kind of final isolation of the human organism. Normal human beings can take a couple of hours of it usually. They like it. Every human being to some extent likes to return to the womb. But after a couple of hours most human beings start going to pieces, short-circuiting. The reason is the deprivation of any outside stimuli. Something has to feed in through some source—some reception source—the skin, ears, nose, the eyes. These things feeding in, they orient a person, tells him when he's thinking, feeling, gives him stimuli for additional thinking. With all these turned off, a person is simply left with a closed circuit. This begins to go round and round and distorts and magnifies and ruptures the whole thinking process. The floater becomes anxious, then very anxious, then he begins having hallucinations, finally becomes completely disoriented. All this happens to a normal human being inside, at the most, three or four hours. No human being should be able to remain sane after four hours of the dead man's float, Barton. But remember how long you lay there in that tank?"
"I didn't care how long it was."
"Three days," Von Ulrich said. "The neurophysiologist in charge there kept checking your reaction and finally he had to take you out of the tank, not because you were short-circuiting, but because he was. The impression was that you would have been delighted with the prospect of doing the dead man's float forever."
"I don't remember it being any special time. It was like a dream, sir, you know."
"I don't know, but I'm trying to find out." Von Ulrich sighed and looked through the spaceport at blackness. "Out here I sometimes find myself wondering what normalcy really is. Things sometimes veer toward the dangerously relativistic." He sat there in the pure one hundred percent silence of the basketball while it accumulated. "There's one thing we've always insisted no human being could tolerate, Barton. Isolation. Sullivan said that a single minute of complete isolation would kill a human being. And you've been in a dead man's float for almost twenty-two years."
"Twenty-two years, sir?"
"Doesn't mean a thing to you does it?"
"Well, sir, it doesn't seem to have had any time in it. I was just here."