There are people in Afghanisan and Russia who are reputed to live to a ripe old age. These exceptionally robust individuals are just getting into their stride at 70. Cases have been reported of men over 120 getting married and having children. Some of these people are said to be over 150 years old. Under such exceptional conditions, who wouldn’t want to go on living forever? But in our societies, to be 70, usually means that you are old; to be 90, often means that you are decrepit. The instinct for self-preservation is the strongest we possess. We cling dearly to life while we have it and enjoy it. But there always comes a time when we’d be better off dead.