By common agreement of all that have arrived at the conception of such a Kind, what is known as Matter is understood to be a certain base, a recipient of FORM-IDEAS. Thus far all go the same way. But departure begins with the attempt to establish what this basic Kind is in itself, and how it is a recipient and of what. Ennead II,4,1

We have remarked that its apparent subsistence is in fact an assemblage of Sensibles, their existence guaranteed to us by sense-perception. But since their combination is unlimited, our division must be guided by the FORM-IDEAS of living beings, as for example the Form-Idea of Man implanted in Body; the particular Form acts as a qualification of Body, but there is nothing unreasonable in using qualities as a basis of division. Ennead VI,3,10