It is hoped that the present volume will supply a want that is really felt by students of philosophy in our universities-the want of an English text-book on General Metaphysics from the Scholastic standpoint. It is the author’s intention to supplement his Science of Logic1 and the present treatise on Ontology, by a volume on the Theory of Knowledge. Hence no disquisitions on the latter subject will be found in these pages: the Moderate Realism of Aristotle and the Schoolmen is assumed throughout. In the domain of Ontology there are many scholastic theories and discussions which are commonly regarded by non-scholastic writers as possessing nowadays for the student of philosophy an interest that is merely historical. This mistaken notion is probably due to the fact that few if any serious attempts have yet been made to transpose these questions from their medieval setting into the language and context of contemporary philosophy. Perhaps not a single one of these problems is really and in substance alien to present-day speculations. The author has endeavoured, by his treatment of such characteristically medieval discussions as those on Potentia and Actus, Essence and Existence, Individuation, the Theory of Distinctions, Substance and Accident, Nature and Person, Logical and Real Relations, Efficient and Final Causes, to show that the issues involved are in every instance as fully and keenly debated-in an altered setting and a new terminology-by recent and living philosophers of every school of thought as they were by St. Thomas and his contemporaries in the golden age of medieval scholasticism. And, as the purposes of a text-book demanded, attention has been devoted to stating the problems clearly, to showing the significance and bearings of discussions and solutions, rather than to detailed analyses of arguments. At the same time it is hoped that the treatment is sufficiently full to be helpful even to advanced students and to all who are interested in the Metaphysics of the Schools . For the convenience of the reader the more advanced portions are printed in smaller type.