The human body contains blood, phlegm, yellow bile and black bile. These are the things that make up its constitution and cause its pain and health. Health is primarily that state in which these constituent substances are in the correct proportion to each other, both in strength and quantity, and are well mixed.

Even when all is known, the care of a man is not yet complete, because eating alone will not keep a man well; he must also take exercise. For food and exercise, while possessing opposite qualities, yet work together to produce health.

If we could give every individual the right amount of nourishment and exercise, not too little and not too much, we would have found the safest way to health.

Everything in excess is opposed to nature.

Where prayer, amulets and incantations work it is only a manifestation of the patient's belief.

There is one common flow, one common breathing, all things are in sympathy.

Men think epilepsy divine, merely because they do not understand it. We will one day understand what causes it, and then cease to call it divine. And so it is with everything in the universe.