It is commonly believed that Aristotle merely uses artefacts as examples or analogical cases. This book, however, shows that Aristotle gives a specific, coherent account of artefacts that in various ways owes much to Plato. Moreover, it proposes a new, definitive solution to the problem of artefacts' substantiality, which comprises two controversial positions: (i) that Aristotle holds a binary view of substantiality according to which artefacts are not substances at all; (ii) that artefacts fail to be substances because they exhibit less of a unity than natural wholes. Finally, responding to the contemporary debate on ordinary objects, the book identifies the main propositions for an ontology of artefacts that aspires to use Aristotle as its authority and can serve as a guideline for current metaphysical discussions. This title is part of the Flip it Open Programme and may also be available Open Access. Check our website Cambridge Core for details.