The knowledge of anything, since all things have causes, is not acquired or complete unless it is known by its causes.

Pain is a sensation produced by something contrary to the course of nature and this sensation is set up by one of two circumstances: either a very sudden change of the temperament (or the bad effect of a contrary temperament) or a solution of continuity.

The different sorts of madness are innumerable.

Pure earth does not petrify, because the predominance of dryness over [i.e. in] the earth endows it not with coherence but rather with crumbliness. In general, stone is formed in two ways only (a) through the hardening of clay, and (b) by the congelation [of waters].

When you do not know the nature of the malady, leave it to nature do not strive to hasten matters. For either nature will bring about the cure or it will itself reveal clearly what the malady really is.

In God alone, essence (what He is) and existence (that he is) coincide.

That whose existence is necessary must necessarily be one essence.

As to the mental essence, we find it in infants devoid of every mental form.

An ignorant doctor is the aide-de-camp of death.

The world is divided into men who have wit and no religion and men who have religion and no wit.

Those who deny the first principle should be flogged or burned until they admit that it is not the same thing to be burned and not burned, or whipped and not whipped.