As every divided kingdom falls, so every mind divided between many studies confounds and saps itself.
Leonardo da VinciThe acquisition of knowledge is always of use to the intellect, because it may thus drive out useless things and retain the good. For nothing can be loved or hated unless it is first known.
Leonardo da VinciIn 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 . . .
Leonardo da VinciNever make heads straight on the shoulders, but turn them aside to the right or to the left, even though they look down, or upward, or straight ahead, because it is necessary for them to look lively and awake and not asleep. And do not depict the front or rear half of the whole person so that too much straightness is displaced, one half above or below the other half; and if you should wish to use stiff figures, do so only in portraying old people.
Leonardo da Vinci