It's not enough that you believe what you see. You must also understand what you see.

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

The men of experiment are like the ant; they only collect and use. But the bee...gathers its materials from the flowers of the garden and of the field, but transforms and digests it by a power of its own.

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.]

Experience is a truer guide than the words of others.

The poet ranks far below the painter in the representation of visible things, and far below the musician in that of invisible things.

One can have no smaller or greater mastery than mastery of oneself.