Recto: notes on proportion, three drawings of right arms, one flexed, two hanging straight; a man standing in profile to the right; back and front views of a male torso. Verso: notes on the proportions of a leg, illustrated by a right leg; notes on the proportions of the foot and the leg; a study of pulleys with notes on dynamics. This drawing was originally folded twice and so numbered in the inventory as four drawings; RCIN 919136 - 919139.

A treatise written by the Roman architect Vitruvius contained the only system of human proportion to survive from Classical times, and formed the basis for Leonardo's first studies of the subject around 1490 (see RCIN 919132). The height of a man was equal to the span of his outstretched arms; a quarter of a span was a cubit. The simplicity of the Vitruvian precepts was undermined when, in RCIN 919136, Leonardo began to measure the model, an individual named as ‘Caravaggio’ and so from that town near Milan. 

On the verso of this sheet he recorded the thickness of his leg at various points, in terms of quarters, fifths, twelfths, and even seventeenths of a head. This drawing is an early example of overwhelming detail in Leonardo’s scientific investigations, with such explanatory notes as ‘mn increases by 1⁄6 from ac and is 7⁄12 of a head’; ‘op is 1⁄10 less than dk and is 6⁄17 of a head’; ‘the hollow on the outside of the knee at r is higher than the hollow on the inside at a by half the thickness of the leg at the foot’; and so on. Such excessive detail prevented Leonardo from arriving at an overall codification of human proportion, and he soon abandoned the attempt.

Text adapted from Leonardo da Vinci: A life in drawing, London, 2018