Test knowledge through experience, be prepared to make mistakes, and be persistent about it.

The human being, creature of eyes, needs the image.

A diamond is just a lump of coal that stuck to its job.

In time and with water, everything changes.

The eye which turns from a white object in the light of the sun and goes into a less fully lighted place will see everything as dark.

Painting is poetry that is seen rather than felt, and poetry is painting that is felt rather than seen.

Those who are in love with practice without knowledge are like the sailor who gets into a ship without rudder or compass and who never can be certain whether he is going. Practice must always be founded on sound theory, and to this Perspective is the guide and the gateway; and without this nothing can be done well in the matter of drawing.