He who does not understand the supreme certainty of mathematics is wallowing in confusion.

A life well used procures a happy death.

Just as courage imperils life, fear protects it.

Drawing is based upon perspective, which is nothing else than a thorough knowledge of the function of the eye.

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

The painter who draws by practise and judgment of the eye without the use of reason is like the mirror which reproduces within itself all the objects which are set opposite to it without knowledge of the same.

You will never have a greater or lesser dominion than that over yourself...the height of a man's success is gauged by his self-mastery; the depth of his failure by his self-abandonment. ...And this law is the expression of eternal justice. He who cannot establish dominion over himself will have no dominion over others.