Truth is so excellent, that if it praises but small things they become noble.

A man was desired to rise from bed because the sun was already up. He replied: "If I had as far to go and as much to do as he has, I should be up by now; but having but a little way to go, I shall not get up yet."

Though I may not . . . be able to quote other authors, I shall rely on that which is much greater and more worthy - on experience.

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

In fact, whatever exists in the universe, in essence, in appearance, in the imagination, the painter has first in his mind and then in his hands ... it lies in his power to create them . . .

You should prefer a good scientist without literary abilities than a literate one without scientific skills

Nothing will be left, Nothing in the air, nothing under the earth, nothing in the waters. All will be exterminated.