But because he is breaking new ground, the going is harder. Matter does not seem to be some principle standing apart from form, but is rooted in the concrete thing as an aspect of the individual by reason of its perfectibility. Matter as potency, then, might be called the 'elasticity or plasticity of esse '. Essence is the primary limitation, a mode of esse , essence as imperfect esse . Matter signifies a secondary limitation, this imperfect being as deficient when a point is reached in the descent of creatures from God at which the esse does not correspond to, is more or less than, one of the Primal Stages of being expressed by the doctrine of the Divine Ideas.
Essences are the primal stages of esse , and make things to be the kind of things they are.
But within this primal stage there is a secondary stage which enables a thing to be more or less what it is, to increase in being without becoming other than what it is. But Carlo also says matter is the limitation of form, the place where form stops. It is a pure potentia . It would seem that he is referring simply to the developmental aspect of an already existing substance - the fact that it is capable of further perfection. It is true that it is the aspect of potentiality, of insufficiency of the existent substance, that is called matter, but it seems to me that this is as far as Thomas Aquinas would go in asserting the being of prime matter as a philosophical principle in its proper metaphysical location.