peared in my brain of all places and I started to have a
peculiar feeling about where the end point in all this reintegrating
routine would lie. Not that the brain operation was a risk; thousands of
people had already gone through it and the substitute organisms had made
no fundamental change in them. It didn't in my case either. But now I
was more second matter than any man in history.

"It's the old question of Achilles' Ship," Dr. Erics told me.

"Never heard of it," I said.

"It's a parable, Treb, about concretised forms of a continuum in its
discrete aspects."

"I see the theoretical question but what has Achilles' Ship to do with
it?"

He furrowed his protoplast brow that looked as youthful as it had a
century ago. "This ship consisted of several hundred planks, most of
them forming the hull, some in the form of benches and oars and a
mainmast. It served its primitive purpose well but eventually sprang a
leak. Some of the hull planks had to be replaced after which it was as
good as new. Another year of hard use brought further hull troubles and
some more planks were removed for new ones. Then the mast collapsed and
a new one was put in. After that the ship was in such good shape that it
could outrace most of those just off the ways."

I had an uneasy feeling about where this parable was leading us but my
mind shied away from the essential point and Erics went relentlessly on.
"As the years passed more repairs were made--first a new set of oars,
then some more planks, still newer oars, still more planks. Eventually
Achilles, an unthinking man of action who still tried to be aware of
what happened to the instruments of action he needed most, realized that
not one splinter of the original ship remained. Was this, then, a new
ship? At first he was inclined to say yes. But this only evoked the
further question: when had it become the new ship? Was it when the last
plank was replaced or when half had been? His confidently stated answer
collapsed. Yet how could he say it was the old ship when everything
about it was a substitution? The question was too much for him. When he
came to Athens he turned the problem over to the wise men of that city,
refusing ever to think about it again."

* * * * *

My mind was now in turmoil. "What," I demanded, "_what_ did they
decide?"

Erics frowned. "Nothing. They could not answer the question. Every
available answer was equally right and proved