Fortunately the great rocks formed a cavern above us. After two days we were rescued. The others had suffered such minor injuries that they were repaired before our craft landed on Nirva. I, though, unconscious and feverish, was in serious condition from skin abrasions and a comminuted cranium. Dr. Erics made the only possible prognosis. My skull had to be removed and a completely new protoskin had to be supplied also.
When I came out of coma Marla was standing at my bedside, smiling down at me. "Do you feel," she stumbled, "darling, I mean, do you feel the way you did?"
I was puzzled. "Sure, I'm Treb Hawley, I'm your husband, and I remember an awful fall of rocks but now I feel exactly the way I always have." I did not even realize that further substitutions had been made and did not believe them when they told me about it.
Now I was an object of curiosity. Upon our return to Earth the newsplastics hailed me as one of the most highly reintegrated individuals anywhere. In all the teeming domain of man there were only seven hundred who had gone through as many substitutions as I had. Where, they philosophised in passing, would a man cease to be a man in the sequence of substitutions?
Philosophy had never been an important preoccupation of mine. It was the only discipline no further ahead in its really essential questions than the Greeks of four thousand years ago. Oh certainly, there had been lots of technical improvements that were fascinating but these were peripheral points; the basic issues could not be experimentally tested so they had to remain on the level of accepted or rejected axioms. I wasn't about to devote much time to them when the whole fascinating field of subatomic mirror numbers was just opening up; certainly not because a few sensational journalists were toying with dead-end notions. For that matter the newsplastics weren't either and quickly went back to the regular mathematical reportage they do so well.
A few decades later, however, I wasn't so cocksure. The old Centaurian virus had reappeared 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.