Just as courage is the danger of life, so is fear its safeguard.

Men wrongly lament the flight of time, blaming it for being too swift; they do not perceive that its passage is sufficiently long, but a good memory, which nature has given to us, causes things long past to seem present.

If a man has a tent made of linen of which the apertures have all been stopped up, and be it twelve bracchia across (over twenty-five feet) and twelve in depth, he will be able to throw himself down from any height without sustaining injury. [His concept of the parachute.]

Instrumental or mechanical science is the noblest and above all others, the most useful.

The painter who has no doubt about his own ability will attain very little.

The water which rises in the mountains is the blood which keeps the mountain in life.

The sun gives spirit and life to the plants and the earth nourishes them with moisture.