Vitruvian Man
The drawing is based on the ideal proportions of a man's body, and how this relates to geometry. This relationship was described by the ancient Roman architect Vitruvius in Book III of his treatise De architectura. Vitruvius wrote the human figure was the main source of proportion among the Classical orders of architecture. He wrote that the ideal body should be eight heads tall. Da Vinci's drawing is traditionally named in honour of the architect.