Just as eating against one's will is injurious to health, so studying without a liking for it spoils the memory, and it retains nothing it takes in.

Even the richest soil, if left uncultivated will produce the rankest weeds.

To lie is vile, to tell truth is excellent, if not noble.

Affective gestures pointing to things near either in time or space should be made with the hand not very far from the body of the person pointing; and if these things are distant, the hand of the painter should be more extended and the face turned toward the person to whom he is addressing the demonstration.

Iron rusts from disuse; water loses its purity from stagnation... even so does inaction sap the vigor of the mind.

For those colours which you wish to be beautiful, always first prepare a pure white ground.

The body of the earth is of the nature of a fish... because it draws water as its breath instead of air.