The human body had changed not at all in the billion years since the building of Diaspar, since the basic design had been eternally frozen in the Memory Banks of the city. It had changed, however, a good deal from its original primitive form, though most of the alterations were internal and not visible to the eye. Man had rebuilt himself many times in his long history, in the effort to abolish those ills to which the flesh was once heir.

Such unnecessary appurtenances as nails and teeth had vanished. Hair was confined to the head; not a trace was left on the body. The feature that would most have surprised a man of the Dawn Ages was, perhaps, the disappearance of the navel. Its inexplicable absence would have given him much food for thought, and at first sight he would also have been baffled by the problem of distinguishing male from female. He might even have been tempted to assume that there was no longer any difference, which would have been a grave error. In the appropriate circumstances, there was no doubt about the masculinity of any male in iaspar. It was merely that his equipment was now more neatly packaged when not required; internal stowage had vastly improved upon Nature’s original inelegant and indeed downright hazardous arrangements.

It was true that that reproduction was no longer the concern of the body, being far too important a matter to be left to games of chance played with chromosomes as dice. Yet, though conception and birth were not even memories, sea remained. Even in ancient times, not one-hundredth part of sexual activity had been concerned with reproduction. The disappearance of that mere one per cent had changed the pattern of human society and the meaning of such words as «father» and «mother»-but desire remained, though now its satisfaction had no profounder aim than that of any of the other pleasures of the senses.

Alvin left his playful contemporaries and continued on toward the center of the park.