of health, sickness, and old age.

alcmaeon says that the preserver of health is an equal proportion of the qualities of heat, moisture, cold, dryness, bitterness, sweetness, and the other qualities; on the contrary, the prevailing empire of one above the rest is the cause of diseases and author of destruction. the direct cause of disease is the excess of heat or cold, the formal cause is excess or defect, the place is the blood or brain. but health is the harmonious commixture of the elements. diocles, that sickness for the most part proceeds from the irregular disposition of the elements in the body, for that makes an ill habit or constitution of it. erasistratus, that sickness is caused by the excess of nourishment, indigestion, and corruptions; on the contrary, health is the moderation of the diet, and the taking that which is convenient and sufficient for us. it is the unanimous opinion of the stoics that the want of heat brings old age, for (they say) those persons in whom heat more abounds live the longer. asclepiades, that the ethiopians soon grow old, and at thirty years of age are ancient men, their bodies being excessively heated and scorched by the sun; in britain persons live a hundred and twenty years, on account of the coldness of the country, and because the people keep the fiery element within their bodies; the bodies of the ethiopians are more fine and thin, because they are relaxed by the sun’s heat, while they who live in northern countries are condensed and robust, and by consequence are more long lived.