In ancient medicine, aging had been interpreted as a natural process due to extinction of innate heat, so that human body become cold and dry. Aristotle used the example of a burning lamp to explain the old age and natural death as the decrease of the flame because of the failure of fuel, the natural moisture. Medieval medicine develops the idea of radical moisture as an innate and substantial humidity, of spermatic origin, which nourishes vital heat, and the biological aging is the result of its consume. Galen's doctrine of marasmos is used to explain signs and symptoms of Old age as illness, so that diet and artificial medicaments are suggested to conserve the primitive and vital factors, and to delay senescence. Still in Renaissance, the proportion and the quantity of radical moisture and innate heat determines the life spam, and the regimina vitae become the only instruments to preserve health and longevity