Dante’s Divine Comedy is a constant presence throughout Leonardo’s work. The poem fascinated artists (from Botticelli to Michelangelo) for the stimulation it offers to the visual imagination. Dante’s epic poetry continuously challenges painting, as Leonardo will recall in his Paragone. But the poem is also an inexhaustible source of philosophical, medical, and scientific knowledge, mediated by commentaries such as the one by Cristoforo Landino.