Herman was a tall, serious, sensitive, healthy, well-muscled young man with an outsize jaw and a brush of red-brown hair. He wore spectacles to correct a slight hyperopia, and they had heavy black rims because he knew his patients expected it. In his off hours, he was fond of books with titles like Personality and the Behavior Disorders, Self-esteem and Sexuality in Women, Juvenile Totem and Taboo: A study of adolescent culture-groups, and A New Theory of Economic Cycles; but he also liked baseball, beer and bebop.

This day, the last of Herman's vacation, was a perfect specimen: sunny and still, the sky dotted with antiseptic tufts of cloud. The trout were biting. Herman had two in his creel, and was casting into the shallow pool across the stream in the confident hope of getting another, when the Universe gave one horrible sliding lurch.

Herman braced himself instinctively, shock pounding through his body, and looked down at the pebbly stream-bed under his feet.

It wasn't there.

He was standing, to all appearances, in three feet of clear water with sheer, black nothing under it: nothing, the abysmal color of a moonless night, pierced by the diamond points of a half-dozen incredible stars.

He had only that single glimpse; then he found himself gazing across at the pool under the far bank, whose waters reflected the tranquil imagery of trees. He raised his casting rod, swung it back over his shoulder, brought it forward again with a practiced flick of his wrist, and watched the lure drop.

Within the range of his vision now, everything was entirely normal; nevertheless, Herman wanted very much to stop fishing and look down to see if that horrifying void was still there. He couldn't do it.

Doggedly, he tried again and again. The result was always the same. It was exactly as if he were a man who had made up his mind to fling himself over a cliff, or break a window and snatch a loaf of bread, or say in a loud voice to an important person at a party, "I think you stink." Determination was followed by effort, by ghastly, sweating, heart-stopping fear, by relief as he gave up and did something else.

All right, he thought finally, there's no point going on with it. Data established: hallucination, compulsion, inhibition. Where do we go from here?

The obvious first hypothesis was that he was insane. Herman considered that briefly, and left the question open. Three or four selected psychoanalyst jokes paraded through his mind, led by the classic, "You're fine, how am I?"