Professor Bergmann is an original thinker who has for many years wrestled with some of the most important and difficult problems of philosophy. Although at first mainly interested in epistemology, he has gradually come to the conclusion that the fundamental questions of philosophy are ontological and that even epistemology is in the last analysis “the ontology of the knowing process.” He holds that by neglecting the explicit formulation of his ontology, a philosopher courts intellectual disaster because the inadequacies of the ontological foundation are likely to affect all philosophical superstructures built on it. In his last book [1], Bergmann explains some of the main features of his ontology in systematic form and criticizes competing systems, especially those of Brentano and Meinong, by comparing them with his own. In the critical parts of his work he tries to show that the competing ontologies are not adequate to the tasks for which they are intended and why this is so. The constructive and the critical parts supplement each other very well, since Brentano's and Meinong's questions and emphases are similar to Bergmann's. Broadly speaking, he regards his own ontology as a phase in a development of ontological insight which consists, at least negatively, in the gradual elimination of three major errors: nominalism, reism, and representationalism.