Alexander of Aphrodisias, reported by Philoponus, On Aristotle’s On the Soul 3 15.65–9 Verbeke 1966

Alexander said that Aristotle says that the intellect exists only in potentiality, but in no way in actuality. Since moreover Aristotle accepts, according to Alexander, those who say that the soul is the place of forms, Xenarchus was deceived by these [words] and suspected that Aristotle was saying that prime matter was intellect; [Xenarchus] judged badly [in this].

Alexander of Aphrodisias, Supplement to On the Soul (On Intellect) (Mantissa 2).106.19–26

(1) Intellect is according to Aristotle of three [types]. One is material intellect. I say ‘material’ not because it is something that underlies like matter – for I say ‘matter’ of something which underlies and is able to become a ‘this-something’ through the presence of some form. (2) Rather, since matter’s being matter [consists] in its having the potentiality for all things, [it follows that] that in which there is potentiality and indeed that which is potential, insofar as it is such, is ‘material’. (3) And so the intellect which is not yet thinking but has the potentiality to come to be like this, is ‘material’, and it is this sort of potentiality of the soul that is the material intellect, not being in actuality any of the extant things, but having the potentiality for becoming all of them, if indeed it is possible for there to be thinking of all the extant things. (Sharples 2004, 24–5)