Painting is concerned with the ten things you can see: these are darkness and brightness, substance and color, form and place, remoteness and nearness, movement and rest.
Leonardo da VinciIron rusts from disuse; water loses its purity from stagnation... even so does inaction sap the vigor of the mind.
Leonardo da VinciWhen you draw a nude, sketch the whole figure and nicely fit the members to it and to each other. Even though you may only finish one portion of the drawing, just make certain that all the parts hang together, so that the study will be useful to you in the future.
Leonardo da VinciVery great charm of shadow and light is to be found in the faces of those who sit in the doors of dark houses. The eye of the spectator sees that part of the face which is in shadow lost in the darkness of the house, and that part of the face which is lit draws its brilliancy from the splendour of the sky. From this intensification of light and shade the face gains greatly in relief and beauty by showing the subtlest shadows in the light part and the subtlest lights in the dark part.
Leonardo da Vinci