The eye is the window of the human body through which it feels its way and enjoys the beauty of the world.
Leonardo da VinciThere are many occasions when the muscles that form the lips of the mouth move the lateral muscles that are joined to them, and there are an equal number of occasions when these lateral muscles move the lips of this mouth, replacing it where it cannot return of itself, because the function of muscle is to pull and not to push except in the case of the genitals and the tongue.
Leonardo da VinciI think it is no small attraction in a painter to be able to give a pleasing air to his figures, and whoever is not naturally possessed of this grace may acquire it by study, as opportunity offers in the following manner: be on the watch to take good parts of many beautiful faces of which the beautiful parts are established by general repute rather than by your own judgement, for you may deceive yourself by selecting faces that resemble your own, since it often seems that such similarities please us; ... so therefore choose the beautiful ones as I tell you and fix them in your mind.
Leonardo da Vinci