Abstract
In Metaphysics vii 1-6, Aristotle argues for the coincidence of the subject-criterion and the essence-criterion, and for the identification of substances with primary subjects. He suggests that form is substance; if the two criteria coincide, form must be both a particular basic subject and a primary essence. In viii-ix, Aristotle defends the identification of matter with potentiality and form with actuality. If this defence is examined prior to a discussion on the rest of the argument in vii, an important part of the argument for identifying form with essence, and hence with substance, can be seen.