Those who are in love with practice without knowledge are like the sailor who gets into a ship without rudder or compass and who never can be certain whether he is going. Practice must always be founded on sound theory, and to this Perspective is the guide and the gateway; and without this nothing can be done well in the matter of drawing.
Leonardo da VinciThe eye is the window of the human body through which it feels its way and enjoys the beauty of the world.
Leonardo da Vinci