Gompertz, more than a century ago, discovered a definite relation between mortality rate and age. For most diseases logarithmic mortality curves are essentially straight lines throughout adult life. Most diseases may be classified as belonging to three groups: (1) the infectious diseases which have a gradual increase in mortality with increasing age. These diseases are also characterized by a high infant mortality rate which falls to a minimum at the age of ten and then gradually increases again. (2) Diseases involving organ or tissue failure. The mortality from these diseases rises at a faster rate than from infectious diseases. (3) Diseases of the cardiovascular-renal system. During youth these have a low mortality which rises so rapidly with increasing age that they become the predominant causes of death in later life. Interestingly enough, unemployment is shown to have a curve which parallels diseases of the cardiovascular-renal system. It is computed that if the mortality rate could be maintained constant at the level of the age of ten, man would have a life expectancy of 800 years and some individuals would survive 22,000 years. There is no proof that we cannot extend active life an extra 100 or 200 years with retention of youthful health, intelligence, and appearance.