Infirmity, that decays the wise, doth ever make the better fool William.Shakespeare, Twelfth Night 1,5 Since antiquity, it has been a dream of mankind to live in eternal youth and thus to attain longevity. Gods and heroes of the myths of many European cultures were always repre­ sented as young. Their youth was one of their most remark­ able attributes, and eternal youth given to a human being from a god was the greatest act of grace. This age old dream of mankind is demonstrated very graphically in one of the most impressive paintings of the Middle Ages, the famous "Jungbrunnen" (Fountain of Youth) by Lucas Cranach. During recent decades, progress in medical and social areas has increased life expectancy at least in the highly developed countries. Although this longevity does not mean eternal youth, it obviously fulfills the ancient desire of mankind. However, to live longer and longer and thus to become older and older also means to live in infirmity over a longer period of life. If progress in medical science continues at the present rate, longevity will as seems inevitable, increase further. At least at this stage, problems of aging might become as important as problems of development. - from Amzon