The forms inhere in the soul-intellect through the material intellect.
In the writings of Albertus Magnus, the influence of Avicenna is combined with that of Averroes, who distinguishes two intellects apart from the separate active intellect: the material intellect, which is pure potentiality (and unique, see section 5.4 below) and the speculative intellect, which is the actuality of the grasped intelligible.
To give one obvious example, the more baroque system set forth in Proclus' Elements is simplified in the Book of the Pure Good to yield a hierarchy identical to that of the Arabic Plotinus (God, Intellect, Soul, material world).
Gersonides agrees with Alexander of Aphrodisias that immortality consists in the intellectual perfection of the material intellect.
It is true that individual men could not reach an intellective knowledge of anything without the material intellect; but it is also true that the material intellect on its own, or with the mere contribution of the active intellect, would not be capable of elaborating any form of knowledge.
For Averroes, as for his predecessors, the intellectual potentiality of a person, represented by the hylic or material intellect, is brought into actuality by the Agent Intellect.
"The past is hidden outside the realm," writes Proust in Swann's Way, "beyond the reach of intellect, in some material object (in the sensation which that material object will give us) of which we have no inkling.
Now, however, Averroes emphasizes that this relation to the imaginative faculty is "incidental" to the nature of the material intellect, its essential relation being with the Agent Intellect.
Inasmuch as the material intellect reflects the knowledge inherent in the Agent Intellect, and inasmuch as this knowledge is grounded in particulars, it follows that humans can have knowledge of particulars; in this acquisition of knowledge lies immortality.
He calls it the natural way: each man has a material intellect which receives them and the intelligibles are relative to each material intellect (Asín Palacios 1942, Ittiṣâl, p. 17; 1968, p. 164).
But Burley's explanation, however interesting, has a weak point, since it does not clarify how it is possible for the material intellect to know an individual existing outside our mind by means of a singular intentional representation that is not present in it, but in elementary thought.
