Call it substantial form.
For Albert the unity of a particular thing is rooted in its particular substantial form, and does not arise as an expression of a higher, mathematical unity, nor can any knowledge of particular natures in themselves be obtained through reflection on being itself, or other higher forms.
Again, this has to do with the soul being his substantial form.
But if Socrates were to lose either his matter in total or his substantial form, he would cease to exist.
For example, according to the Scholastic theory, a lump of gold is an instance of gold because its matter possesses the substantial form of gold which causes all of the properties of gold, e.g., malleability, yellowish color, heaviness, etc.
In 75.7, Thomas argues that the intelletual soul is not of the same species as an angel, because it is a substantial form of an animal.
Because the soul is a substantial form, it is not complete in its nature, and cannot be a spiritual substance like an angel, properly speaking.
The thing with which it is uniquely correlated, and of which it is the substance, is not one of its instances, but is the substantial form itself.
Taken in contrast to the Aristotelian doctrine that each existent has a single substantial form (ensuring its unity as a substance), "the plurality of forms" doctrine describes the Universal Hylomorphic sense in which each existent has a number of essential forms (and matters).
