A wave is never found alone, but is mingled with as many other waves as there are uneven places in the object where the said wave is produced.
Leonardo da VinciAfter painting comes Sculpture, a very noble art, but one that does not in the execution require the same supreme ingenuity as the art of painting, since in two most important and difficult particulars, in foreshortening and in light and shade, for which the painter has to invent a process, sculpture is helped by nature. Moreover, Sculpture does not imitate color which the painter takes pains to attune so that the shadows accompany the lights.
Leonardo da Vinci