Stanislaw Lebniewski’s interests were, for the most part, more philosophical than mathematical. Prior to taking his doctorate at Jan Kazimierz University in Lvov, Lebniewski had spent time at several Continental universities, apparently becoming relatively attached to the philosophy of one of his teachers, Hans Cornelius? to the chapters of John Stuart Mill’s System of Logic that dealt specifically with semantics, and, in general, to studies of general grammar and philosophy of language.3 In these several early interests are already to be found the roots of the work that was to occupy LeSniewski’s life: a search for a definitive doctrine of what sorts of things there are in the world, or better, of what language must be like if it is adequately and eflciently to represent the world.4 Upon his return to Poland, LeSniewski enrolled in the Jan Kazimierz University, where he came under the influence of Kazimierz Twardowski and Jan Lukasiewicz. Twardowski has been called “the father of Polish philosophy” because of his tremendous influence upon Lebniewski, Lukasiewicz, Tadeusz Kotarbihski and so many of the great Polish philosophers. Like Cornelius, Twardowski had himself been heavily influenced by Franz Brentano. Unlike Cornelius, however, who probably was influenced by Brentano through Carl Stumpf - a colleague of Cornelius’s at Munich, and himself a student of Brentano’s - Twardowski had studied under Brentano. Thus, the move from ’ I am grateful to Judson Webb and Paul Saga1 for inspiration in this as in many other projects. * Cornelius was a member of the so-called ‘Austrian school’ of psychologists and philosophers. The distinguishing characteristic of this school was its advocacy of the ‘act psychology’ of Franz Brentano, as opposed to the ‘content psychology’ of Wilhelm Wundt. Brentano had emphasized the doctrine that psychical phenomena are to be thought of as acts. When one sees a color, the color itselfis not mental; it is the seeing the act - that is mental. The act always, however, implies an object or refers to a content. Cornelius himself was only partially committed to this view, and contributed toward a partial analysis of the alleged ‘acts’ in terms of complex contents, an analysis that was later to lead (in the work of Friedrich Schumann) to a compromise of sorts between the act and content schools, but one that was framed in Wundtian terms (see [Boring 19571, 356-361 and 439-447). The influence of Brentano upon Cornelius was great, however.