On this sheet Leonardo studies the flow of water past an obstacle, exemplifying his uncanny ability to fix a momentary impression in his mind and capture it on paper with absolute conviction. In his notes he compares the swirling water to plaited hair. The bearded old man seated on a rocky outcrop appears to be gazing at the flows of water, but this is illusory, as the sheet was folded when the drawings were made. Melzi's number 57.

The movement of water haunts Leonardo’s work in many fields. In his landscapes it is a symbol of natural processes over unconscionable timespans; in his civil engineering it is a powerful but tractable adversary; and in his scientific studies it is a pure element, responding perfectly to external forces in a manner that can be observed and analysed.

The architectural studies on the reverse of the sheet are probably connected to Leonardo's work at Villa Melzi.

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