Did you know that you can determine the size and position of different parts of your face using string and some rules about the human body? It's not magic ... it's mathematical! Pedagogical Side: This segment illustrates how an artist can accurately determine the location of eyes, ears, nose, chin, and lips on a drawing based on rules that can predict body proportions. More than 500 years ago, artist and inventor Leonardo da Vinci made a drawing called "Vetruvian Man" which shows how the proportions of the human body relate to a square and a circle.