ABSTRACT. Smith maintains that Brentano conceives his own theory of substance as a refined and perfected version of the Aristotelian theory. According to Mulligan and Smith, Brentano argues that a range of different habits and training are necessary preconditions of noticing. McDonnell observes that, for Brentano, our consciousness contains a structural unity of its own. Zahavi emphasizes that, according to Brentano, all mental states are characterized by their intentional directedness, they are all conscious of objects. Albertazzi points out that Brentano’s doctrine tries to conciliate the presence of an often irreducible transcendent foundation of perception with its immanent and equally irreducible categorization by the intentional acts.