da Vinci's Vitruvian Man

Renaissance artists were fascinated by the human body for several reasons. God made humans in His own image, so the human body must be perfect, reflecting the perfection of God Himself. Renaissance artists were also obsessed with proportions, and none more than that of the human body. With arms and legs extended, the human body fits into a square and a circle—the perfect geometrical forms. This was astonishing to them and became a foundation for the whole philosophy of the Renaissance that "Man is the measure of all things."