I also maintain that clear knowledge of natural science must be acquired, in the first instance, through mastery of medicine alone.

Through seven figures come sensations for a man; there is hearing for sounds, sight for the visible, nostril for smell, tongue for pleasant or unpleasant tastes, mouth for speech, body for touch, passages outwards and inwards for hot or cold breath. Through these come knowledge or lack of it.

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.

When doing everything according to indications, although things may not turn out agreeably to indication, we should not change to another while the original appearances remain.

The physician must have at his command a certain ready wit, as dourness is repulsive both to the healthy and the sick.

Silence is not only never thirsty, but also never brings pain or sorrow.

That which is used - develops. That which is not used wastes away.