By investigating Aristotle's belief (as stated in the Metaphysics) at all living beings are substances, this book answers the question of whether artifacts are substances. By arguing that the two criteria of substantiality are "eternity" and "actuality" (thereby excluding some organisms), and by covering Aristotle's theory of an and nature as well as his embryology, Aristotle on Artifacts offers a novel way of dealing with a number of highly controversial issues and variety of metaphysical problems.