It is better to imitate ancient than modern work.

Reprove your friend in secret and praise him openly.

Perspective is nothing more than a rational demonstration applied to the consideration of how objects in front of the eye transmit their image to it, by means of a pyramid of lines. The Pyramid is the name I apply to the lines which, starting from the surface and edges of each object, converge from a distance and meet in a single point.

Great love is born of great knowledge of the thing that is loved, and if you do not know it, you can love it little or not at all.

If you are alone you belong entirely to yourself. If you are accompanied by even one companion you belong only half to yourself or even less in proportion to the thoughtlessness of his conduct and if you have more than one companion you will fall more deeply into the same plight.

The supreme misfortune is when theory outstrips performance

Fix your course on a star and you'll navigate any storm.