 Following Aquinas, Maritain holds that metaphysics deals with being as being (ens inquantum ens), i.e., it “investigates the first principles of things and their highest causes” (Preface to Metaphysics, 1934 [1939: 27]). And Maritain also holds that there are certain fundamental metaphysical questions to which Aquinas’s responses are largely correct, though they may not be complete as they stand. Maritain adopts, against John Duns Scotus, Aquinas’s general position on analogy, being, and on the need for analogical terms and concepts. Again, in answer to the problem of unity and plurality—e.g., how can a thing be individual and distinct and yet a member of a class of things of the same kind?—Maritain follows Aquinas: that we have to distinguish what a thing is (its nature or essence, which it shares with things of the same kind) from the fact that it is (i.e., that it has its own ‘act of existing’). When it comes to the analysis of the nature and the unity of sensible beings, including human beings, Maritain employs Aquinas’s distinction between the form and the matter of a thing; nature or essence reflects the form, whereas the individuality is determined by the matter.