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.]

The painter has the Universe in his mind and hands.

Those who are enamoured of practice without science are like a pilot who goes into a ship without rudder or compass and never has any certainty of where he is going. Practice should always be based upon a sound knowledge of theory.

I have discovered that a screw-shaped device such as this, if it is well made from starched linen, will rise in the air if turned quickly.

O sleepers! what a thing is slumber! Sleep resembles death. Ah, why then dost thou not work in such wise as that after death thou mayst retain a resemblance to perfect life, when, during life, thou art in sleep so like to the hapless dead?

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

It is a far worthier thing to read by the light of experience than to adorn oneself with the labors of others.