The focus of the book, which consists in three studies, can be described in the following aspects: Considerations on Aristotle's universals, reconstruction of Aristotle's critics to Plato' s ideas in Aristotle's lost work “On Ideas”, analysis of Aristotle's substance in the works Categories, Metaphysics, On the Soul, Posterior Analytics, Physics. My point of view is that Aristotle refuses every aspect of Plato's ideas in a radical way. I analyze Aristotle's conditions for a synonymy of predication and compare them with the (...) condition for a not-homonymy of predication in the Argument from Relatives of “On Ideas”. My reflections on substance plead for the presence of a plurality of values of substance in the works of Aristotle: substance can be, for instance, the individual biological entity or the essence/nature/form of a biological entity; a coexistence of both values can be noticed in the different works of Aristotle. (shrink)