M and N, the last two books of the Metaphysics, are Aristotle's only sustained venture into the philosophy of mathematics. In them, he criticizes Plato's theories and suggests alternatives of his own. This commentary concentrates on the continuing philosophical interest of these books rather than on scholarly controversies, and will provide a clear introduction for students, including those without Greek, to an unjustly neglected part of Aristotle's work. This paperback edition replaces the outstandingly successful hardback. 'Dr Annas's translation is clear, readable, and accurate...an enjoyable volume, stimulating both as intellectual history and as philosophical argument.' Times Literary Supplement