On the quest for the holy grail for as long as we live

True, everyone born before Aug. 4, 1900, has proved mortal (the world's oldest-known living person, a Japanese woman named Nabi Tajima, was born on that date). But the past is only an imperfect guide to the future, as the effervescent present is ceaselessly teaching us. But our children, our grandchildren -- or if not them, theirs -- may, conceivably, be the beneficiaries of the greatest revolution ever: the conquest of death. Immortality is an ancient dream. A Chinese king of the third century B.C. dispatched a sage, Xu Fu by name, on a quest for the elixir of life.