Those who become enamoured of the art, without having previously applied to the diligent study of the scientific part of it, may be compared to mariners who put to the sea in a ship without rudder or compass and therefore cannot be certain of arriving at the wished for port.

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

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

You must grow in patience when you meet with great wrongs, and they will then be powerless to vex your mind.

Happy will they be who lend ear to the words of the dead.

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.

Ask counsel of him who rules himself well.