A drawing of the head of a youth, with long wavy hair, bending forward and inclined slightly away from the spectator. He is seen almost in profile to the left, with his lips parted and his eyes raised. Melzi's number 27.

Leonardo’s greatest work to reach completion was the Last Supper, painted for Ludovico Sforza, Duke of Milan, in the refectory of Santa Maria delle Grazie. This revolutionary exercise in the depiction of emotion shows the reaction of the Disciples to Christ’s announcement of his imminent betrayal. The painting was complete by 1498, but Leonardo’s experimental technique was soon deteriorating, and what we see now is a ghost of his intentions.

Leonardo must have executed many drawings as he refined the composition, but only a handful survive. In this study for St Philip, leaning devotedly towards Christ, Leonardo fixes his ideal of divinity with a heavily drawn profile and a uniform finish.

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