The Vitruvian Man
This famous drawing called "The Vitruvian Man" was made around 1490 by Leonardo Da Vinci in the Renaissance period.
A naked male depicted in this drawing is inscribed both in a circle and in a square. This drawing along with accompanying notes is called the Canon of Proportions and is on display in the Gallerie dell' Accademia in Venice, Italy.
De Architecture, the famous treatise on architecture was authored by Marcus Vitruvius a Roman architect in 1 BC. The treatise comprised of ten different books, which dealt with the aspects of architecture, city planning, and machines. In Book III of this treatise, in his discussion of temples is where the concept of the Vitruvian Man emerges. This drawing of Leonardo was based on Vitruvius' description in harmonizing the relation between parts of the body looking for perfection.
The emphasis on this drawing is on the rationalization of geometry, where small numbers build the composition. This picture also represents Leonardo's attempt to relate man to nature based on his beliefs that the workings of the human body are analogous to the workings of nature. It is also believed that Leonardo symbolized the material existence by the square and the spiritual existence by the circle.
This drawing is no doubt, one of the masterpieces of the European Renaissance.
Some of the sources from which i had got this information are listed below
http://leonardodavinci.stanford.edu/submissions/clabaugh/history/leonardo.html
http://www.aiwaz.net/Leonardo/vitruvianman/index.html
http://thealchemicalegg.com/VitruviusN.html