A human lifetime is 80 years long on average. A person imagines and organizes his life with that in mind. What I have just said everyone knows, but only rarely do we realize that the number of years granted us is not merely a quantitative fact, an external feature (like nose length or eyes color), but is part of the very definition of the human. A person who might live, with all his faculties, twice as long, say 160 years, would not belong to our species. Nothing about his life would be like…
