When you look at a wall spotted with stains...you may discover a resemblance to various landscapes, beautiful with mountains, rivers, rocks, trees. Or again, you may see battles and figures in action, or strange faces and costumes, and an endless variety of objects which you could reduce to complete and well-drawn figures.

Obstacles cannot crush me. Every obstacle yields to stern resolve. He who is fixed to a star does not change his mind.

People of higher talent work, even if they seem to do nothing

The Book of the science of Mechanics must precede the Book of useful inventions.

Who would believe that so small a space could contain the images of all the universe?

Obstacles cannot bend me. Every obstacle yields to effort.

In rivers, the water that you touch is the last of what has passed and the first of that which comes; so with present time.