The merit of painting lies in the exactness of reproduction. Painting is a science and all sciences are based on mathematics. No human inquiry can be a science unless it pursues its path through mathematical exposition and demonstration.

Wisdom is the daughter of experience

Perspective is a most subtle discovery in mathematical studies, for by means of lines it causes to appear distant that which is near, and large that which is small.

Do not reveal, if liberty is precious to you; my face is the prison of love.

Medicine is the restoration of discordant elements; sickness is the discord of the elements infused into the living body.

Anyone who invokes authors in discussion is not using his intelligence but his memory.

What induces you, oh man, to depart from your home in town, to leave parents and friends, and go to the countryside over mountains and valleys, if it is not for the beauty of the world of nature?