This drawing is certainly one of the most precious artworks in the collection and in the city of Milan. It is the largest renaissance cartoon that has survived to this day, and was made by Raphael as a preparatory work for the Stanza della Segnatura in the Vatican, which was commissioned by Julius II. It entered Federico Borromeo’s collection in 1626, when he purchased it from the widow of Fabio Borromeo Visconti for the massive sum of six hundred imperial lire, even though it had actually been on loan to the Ambrosiana since 1610. Although it is known as The School of Athens, the more exact title is Philosophy, as suggested by the allegory of the same subject painted on the vault above the fresco in the Stanza della Segnatura, as part of a very complex iconographic project. At the centre we see the two greatest philosophers, Plato (painted with the likeness of Leonardo, with his finger pointing upwards and identifiable by the Timaeus he is holding, one of his works that had enormous influence on later philosophy) and Aristotle, who is identified by his book of Ethics.