To me it seems that those sciences are vain and full of error which are not born of experience, mother of all certainty, first-hand experience which in its origins, or means, or end has passed through one of the five senses.

Let the painter composing narrative pictures take pleasure in wealth and variety, and avoid repeating any part that occurs in it, so that the uniqueness and abundance attract people to it and delight the eye of the observer. I say that a narrative painting requires (depending on the scene), wherever the eye falls, a mixture of men of diverse appearances, of diverse ages and dress, combined together with women, children, dogs, horses, buildings, fields, and hills.

Given the cause nature produces the effect in the briefest manner that it can employ.

We might say that the earth has the spirit of growth; that its flesh is the soil.

All objects transmit their image to the eye in pyramids and the nearer to the eye these pyramids are intersected the smaller will the image appear of the objects which cause them.

The painter will produce pictures of little merit if he takes the works of others as his standard.

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.]