It has been recently claimed that the single most important work produced by a member of the Lvov-Warsaw school is Tarski's article on truth.¹ Tarski's work belongs to a tradition of study in which the influence of Brentano's thought was ensured by the mediation of Twardowski. The paper by Wolenski and Simons to which I refer analyses the positions of the leading members of the Lvov-Warsaw school, in particular the theories of Twardowski, Łukasiewicz, Kotarbinski, Leśniewski and Tarski. I shall here make closer scrutiny of the theories of Brentano and certain other members of his school. As well as Brentano, therefore, I shall be discussing Marty, Meinong and Husserl.