The faculty of imagination is both the rudder and the bridle of the senses.

Let not your rage or malice destroy a life.

The worst evil which can befall the artist is that his work should appear good in his own eyes.

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.

O sleepers! what a thing is slumber! Sleep resembles death. Ah, why then dost thou not work in such wise as that after death thou mayst retain a resemblance to perfect life, when, during life, thou art in sleep so like to the hapless dead?

We know more about the movement of celestial bodies than about the soil underfoot.

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