Robert Heinlein's Methuselah's Children: breeding for longevity and one mutant immortal;
Poul Anderson's World Without Stars: the antithanatic;
Anderson's The Boat Of A Million Years: mutants, then artificial longevity;
James Blish's Cities In Flight: anti-agathics;
Blish's "A Style In Treason": "...indefinitely prolonged physical vigor..." (Anywhen, New York, 1970, p. 14).
Anderson's mutant immortals avoid insanity from endless memory accumulation by marshalling their own inner resources whereas the beneficiaries of his "antithanatic" have their memories periodically edited by artificial means. They retain recent memories and the overall structure of their lives but not the many biographical details for which they can consult written records.
The indefinitely vigorous people of Blish's "A Style In Treason" have found different uses for memory control:
"After a while, it became difficult to remember who one was supposed to be - and to remember who one was was virtually impossible. Even the Baptized, who had had their minds dipped and then rechannelled with only a century's worth of memories, betrayed to the experienced eye a vague, tortured puzzlement, as though still searching in the stilled waters for some salmon of ego they had been left no reason to suspect had ever been there. Suicide was unconcealedly common among the Baptized..." (p. 14).
So sanity is not a priority. These Blish characters are "...tired..." and decadent by contrast with the intergalactic expansion and dynamism of Anderson's antithanatic-users so would immortality be a curse or could it be put to constructive use? Science fiction writers show us both options.
