There is no higher or lower knowledge, but one only, flowing out of experimentation.

If you find from your own experience that something is a fact and it contradicts what some authority has written down, then you must abandon the authority and base your reasoning on your own findings.

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.

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.

O Lord, thou givest us everything, at the price of an effort.

I roamed the countryside searching for answers to things I did not understand.

For those colours which you wish to be beautiful, always first prepare a pure white ground.