Men of genius sometimes accomplish most when they work least, for they are thinking out inventions.
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 VinciIt is no small benefit on finding oneself in bed in the dark to go over again in the imagination the main lines of the forms previously studied, or other noteworthy things conceived by ingenious speculation.
Leonardo da Vinci