... we might say that the earth has a spirit of growth; that its flesh is the soil, its bones the arrangement and connection of the rocks of which the mountains are composed, its cartilage the tufa, and its blood the springs of water.

The eye transmits its own image through the air to all the objects which face it, and also receives them on its own surface, whence the "sensus communis" takes them and considers them.

Just as a well-filled day brings blessed sleep, so a well-employed life brings a blessed death.

No human investigation can claim to be scientific if it doesn't pass the test of mathematical proof.

Though I may not . . . be able to quote other authors, I shall rely on that which is much greater and more worthy - on experience.

Whatever you think matters - doesn't. Follow this rule, and you will add decades to your life. Rodger Rosenblatt As a well spent day brings happy sleep, so life well used brings happy death.

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.