The Vitruvian Man (Italian: Le proporzioni del corpo umano secondo Vitruvio, "The proportions of the human body according to Vitruvius"), or simply L'Uomo Vitruviano, is a drawing by Leonardo da Vinci around 1490. It is accompanied by notes based on the work of the architect Vitruvius. The drawing, which is in pen and ink on paper, depicts a man in 2 superimposed positions with his arms and legs apart and inscribed in a circle and square. The drawing and text are sometimes called the Canon of Proportions or, less often, Proportions of Man. It is kept in the Gabinetto dei disegni e stampe of the Gallerie dell'Accademia, in Venice, Italy, under reference 228. Like most works on paper, it is displayed to the public only occasionally.
The drawing is based on the correlations of ideal human proportions with geometry described by the ancient Roman architect Vitruvius in Book III of his treatise De architectura. Vitruvius described the human figure as being the principal source of proportion among the classical orders of architecture. Vitruvius determined that the ideal body should be eight heads high. Leonardo's drawing is traditionally named in honor of the architect.... (https://en.wikipedia.org/wiki/Vitruvian_Man)
After detailing human proportions, Vitruvius went on to describe, in a memorable visualization, a way to put a man in a circle and square in order to determine the ideal proportion of a church:
...And just as the human body yields a circular outline, so too a square may be found from it. For if we measure the distance from the soles of the feet to the top of the head, and then apply that measure to the outstretched arms, the breadth will be found to be the same as the height, as in the case of a perfect square.
It was a powerful image. But as far as we know, no one of note had made a serious and precise drawing along these lines in the fifteen centuries since Vitruvius composed his description. Then, around 1490, Leonardo and his friends proceeded to tackle this depiction of man spread-eagle amid a church and the universe....