To save for later…
A paraphrase of the argument by Albert Magnus in George Reilly’s The Psychology of Albert the Great: Compared with That of Saint Thomas (1934), 39.
“The act of understanding is abstract and free from the conditions and limitations of matter. Now since the ‘intelligible’ has a twofold relation, one to the intellect, the other to the thing whose image it is, the freedom in the ‘intelligible’ must come from either of these two things to which it is related. But not from the thing, which is often material or at least bound up with matter, therefore it must be from the intellect. Accordingly, since abstraction is simple, immaterial and incorporeal, the intellect is essentially simple and incorporeal and likewise the rational soul.”