By then Marla had a perfect artificial ear and both of my sons had lost their congenitally diseased livers. There was nothing extraordinary about our family; only in my case were replacements somewhat above the world average. I am proud to say that I was among the first thousand who made the pioneer voyage on hyperdrive to the star group beyond Centaurus. We returned in triumph with our fantastic but true tales of the organic planet Vita and the contemplative humanoids of Nirva who will consciousness into subjectively grasping the life and beauty of subatomic space. The knowledge we brought back assured that the fatal disease of ennui could never again attack man though they lived to Aleph Null. On the second voyage Marla, Robert and Neil went with me. This took a little political wrangling but it was worth throwing my merit around to see them benefit from Nirvan discoveries even before the rest of humanity. Planetary Council agreed my services entitled me to this special consideration. Truly I could feel among the blessed. Then I volunteered for the small expeditionary force to the 38th moon that the Nirvans themselves refused to visit. They tried to dissuade us but, being of a much younger species, we were less plagued by caution and went anyway. The mountains of this little moon are up to fifteen miles high, causing a state of instability that is chronic. Walking down those alabaster valleys was a more awesome experience than any galactic vista I have ever encountered. Our aesthetic sense proved stronger than common sense alertness and seven of us were buried in a rock slide. * * * * * 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?