The books translated in this volume are fourth, fifth, and sixth in the traditional ordering of Aristotle's Metaphysics. The nature and scope of metaphysics are discussed in gamma and epsilon. A subtle examination of the principles of non-contradiction and excluded middle occupies the latter part of gamma. Delta is in the form of a philosophical lexicon. All three books contain important material on being, substance, `accident', unity, truth, cause, and other such concepts. The translation is very close to the Greek, as an aid to students who cannot check the English version against the original. It is followed by an interpretative and critical commentary. For this new edition Mr Kirwan has added a substantial section of further comment on several central issues, and considerably expanded the bibliography.