Apart from the opposite semantic attitudes, the main difference between Late Medieval Realists and Nominalists lies in the antithetic evalutation of the nature and ontological status of essences. In the article a very interesting exemple of the medieval realist approach to the problem of essence, that of Walter Burley, is discussed. Because of Ockham's criticisms of the traditional realist conceptions, Burley's ontological convictions evolved over the years from a quite original version of the moderate realism inspired by Averroe's doctrine on (...) essence, to the radical (and somehow Platonic) form of realism proper to his final theories. (shrink)