‘There is’, Sigmund Freud tells us in his psychobiography of the great artist, ‘only one place in his scientific notebooks where Leonardo [da Vinci] inserts a piece of information about his childhood’. In the course of a discussion of the mechanics of the flight of vultures, Leonardo interjects this anecdote: This single and fleeting vista onto the childhood of Leonardo acts for Freud as a key to unlocking what Ernst Kris and Otto Kurz will call ‘the riddle of the artist’. As Freud writes at the start of his biographical sketch: ‘Leonardo da Vinci (1452–1519) was admired even by his contemporaries as one of the greatest men of the Italian renaissance; yet in their time he had already begun to seem an enigma, just as he does to us to-day’...