A Timeless History
The idea is Roman. Vitruvius wrote that a well-made body fits a circle centred on the navel and a square as wide as it is tall — and that a temple should be proportioned the same way, every part a fraction of the whole. Francesco di Giorgio drew it around 1480; Leonardo drew his in Milan around 1490; Cesare Cesariano printed one in the first Italian Vitruvius, Como 1521. Venice bought Leonardo's sheet in 1822.
SourceVitruvius, De architectura III.1, tr. M. H. Morgan 1914 — Project Gutenberg · Gallerie dell'Accademia di Venezia, catalogue entry — gallerieaccademia.it · Library of Congress, cph.3c10321 (Cesariano 1521) · Image: Cesariano, Como 1521 — LoC (PD)
Science In Action
Two centres: the circle sits on the navel, the square lower, at the groin — that is how one body fits both • The square: arm span equals height, so fingertips and soles touch its four sides • The circle: the legs open until the head drops by 1/14 of the height; between them, an equilateral triangle • Roman ratios: face one tenth, head one eighth, foot one sixth of the height — Leonardo: foot one seventh
SourceLeonardo's text on the sheet (transcription, Gallerie dell'Accademia / Wikipedia) · Vitruvius III.1.2–3 · Image: Leonardo, Vitruvian Man, detail — Gallerie dell'Accademia, Venice, via Wikimedia Commons (PD)
Arts
Artists took the rule and kept measuring. Albrecht Dürer spent years on his Four Books on Human Proportion (Nuremberg, 1528): page after page of bodies and heads ruled into fractions, printed months after his death. Leonardo's sheet is itself the artwork — pen and brown ink, mirror writing above and below, a scale bar under the feet — reproduced so often that it now stands for the Renaissance itself.
SourceThe Metropolitan Museum of Art, 31.54.106–109 — metmuseum.org · Gallerie dell'Accademia di Venezia · Image: Dürer, Vier Bücher von menschlicher Proportion, 1528 — The Met (CC0)
Applications Today
Bodies are still measured, and things are sized to them. NASA photographed its AX-5 hard suit of the 1980s in Leonardo's pose to show how far its joints move. Clinics use arm span to estimate the height of a patient who cannot stand — and find it about 5 per cent longer than height, not equal. And since 2002 the figure has been in every Italian pocket, on the 1-euro coin's national side, chosen by television vote.
SourceNASA Ames Research Center, image 467808 (AX-5) — nasa.gov · Annals of Thoracic Medicine 3 (2008), arm span and height — PubMed 19561887 · European Commission, national sides of euro coins: Italy — economy-finance.ec.europa.eu · Image: NASA AX-5 suit — NASA (PD)
The sheet is about 34 by 25 cm, pen and ink on paper; Venice keeps it out of the light and shows it rarely.
A pariquadrata superficie humani corporis perdistincta eo naturali centro umbilici circulum excipere: et in eo quadratum minorem inscribere, fig. a (Book III) — the 'homo ad circulum' woodcut — Cesare Cesariano (Italian, 1475–1543), in his Italian translation of Vitruvius, De architectura — 1521 (Como, Gottardo da Ponte) — Library of Congress, Prints and Photographs Division, digital ID cph.3c10321; scan via Wikimedia Commons (3286 × 4096), cropped to the cartouche, the grid, head and arms — the figure is cut above the waist (no nudity in the crop) — LoC LCCN 2006681079
