Nor can we, on the other hand, think that matter is simply ABSOLUTE MAGNITUDE. Enneads III,6,17
Magnitude is not, like Matter, a receptacle; it is an Ideal-Principle: it is a thing standing apart to itself, not some definite Mass. The fact is that the self-gathered content of the Intellectual Principle or of the All-Soul, desires expansion (and thereby engenders secondaries): in its images – aspiring and moving towards it and eagerly imitating its act – is vested a similar power of reproducing their states in their own derivatives. The Magnitude latent in the expansive tendency of the Image-making phase (of Intellect or All-Soul) runs forth into the ABSOLUTE MAGNITUDE of the Universe; this in turn enlists into the process the spurious magnitude of Matter: the content of the Supreme, thus, in virtue of its own prior extension enables Matter – which never possesses a content – to exhibit the appearance of Magnitude. It must be understood that spurious Magnitude consists in the fact that a thing (Matter) not possessing actual Magnitude strains towards it and has the extension of that straining. All that is Real Being gives forth a reflection of itself upon all else; every Reality, therefore, has Magnitude which by this process is communicated to the Universe. Enneads III,6,17
Particular entities thus attain their Magnitude through being drawn out by the power of the Existents which mirror themselves and make space for themselves in them. And no violence is required to draw them into all the diversity of Shapes and Kinds because the phenomenal All exists by Matter (by Matter’s essential all-receptivity) and because each several Idea, moreover, draws Matter its own way by the power stored within itself, the power it holds from the Intellectual Realm. Matter is manifested in this sphere as Mass by the fact that it mirrors the ABSOLUTE MAGNITUDE; Magnitude here is the reflection in the mirror. The Ideas meet all of necessity in Matter (the Ultimate of the emanatory progress): and Matter, both as one total thing and in its entire scope, must submit itself, since it is the Material of the entire Here, not of any one determined thing: what is, in its own character, no determined thing may become determined by an outside force – though, in becoming thus determined, it does not become the definite thing in question, for thus it would lose its own characteristic indetermination. Enneads III,6,17
Matter, then, wears Magnitude as a dress thrown about it by its association with that ABSOLUTE MAGNITUDE to whose movement it must answer; but it does not, for that, change its Kind; if the Idea which has clothed it were to withdraw, it would once again be what it permanently is, what it is by its own strength, or it would have precisely the Magnitude lent to it by any other form that happens to be present in it. Enneads III,6,18