O time, swift robber of all created things, how many kings, how many nations hast thou undone, and how many changes of states and of various events have happened since the wondrous forms of this fish perished here in this cavernous and winding recess. Now destroyed by time thou liest patiently in this confined space with bones stripped and bare; serving as a support and prop for the superimposed mountain.

The light and heat of the universe comes from the sun, and its cold and darkness from the withdrawal of the sun.

A bird is an instrument working according to mathematical law, which instrument it is within the capacity of man to reproduce with all its movements.

To me it seems that those sciences are vain and full of error which are not born of experience, mother of all certainty, first-hand experience which in its origins, or means, or end has passed through one of the five senses.

The five senses are the ministers of the soul.

The limiting surface of one thing is the beginning of another.

Painting is concerned with the ten things you can see: these are darkness and brightness, substance and color, form and place, remoteness and nearness, movement and rest.