The immediate reason for which artefacts are not substances is arrived at only by means of the consideration of matter as parts and the focus on the relation of parts and whole, which is undertaken in this chapter. Indeed, artefacts fail to satisfy the substantiality criterion, according to which no substance is composed of parts present in it in actuality (Met. Z 13). I show that Aristotle regards living beings as constituted of parts in potentiality, while he conceives of artefacts as constituted of parts present in actuality. Because their parts are in actuality, artefacts are not as unified as substances, but because artefacts still possess an inherent form, they cannot be downgraded to mere heaps. Thus, artefacts are hylomorphic compounds, but not substances at all.