Recto: a nude man standing, facing the spectator, with arms outstretched. Another is kneeling beside him, to his right, so that his head just fits under the standing man's arm; to the left of the main figure is a third man, seated, measured for proportion; with notes on human proportion on the left side of the sheet. Verso: a four line note on proportion.

The system of human proportions in the central drawing on this sheet follows that set out in the treatise On Architecture by the Roman architect Vitruvius (first century bc). Accordingly, the height of the man is equal to the span of his outstretched arms; a quarter of his height is the cubit, marked off horizontally at the knees, pubis and between the armpits, and vertically at the elbows and down the centre of the chest. The same proportions are seen in Leonardo’s most famous drawing, the ‘Vitruvian man’ standing with arms outstretched in a square and circle (Venice, Accademia). The notes explain the two subsidiary diagrams: ‘if a man kneels he will diminish by a quarter part of his height’, and ‘the umbilicus is [then] the middle of his height’; and ‘the middle of a man who sits […] is below the breast and below the shoulder’.

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