"Leeches should be kept a day before applying them. They should be squeezed to make them eject the contents of their stomachs."

"The proof of the existence of the soul is that you doubt."

"Time is a sword; if you do not cut it, it will cut you."

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

"Medicine considers the human body as to the means by which it is cured and by which it is driven away from health."