Chapter 8

The intrinsic order of being in corporeal entity -
The concept of act -
Substantial and accidental acts

840. So far, we have considered matter under the guidance of experience, that is, of perception, through which our understanding is placed in communication with matter and hence with its concept. Our consideration has shown us the nature of the intrinsic order of being in a corporeal entity.

What we see is this. In this entity, which is called 'body' and 'matter', there is an act prior to all others, on which all others are founded, and without which they cannot be thought. We can think this prior act perfectly well without thinking of the other acts, although we have to understand that this act, when realised, is accompanied by the other acts which are in part variable. This first act that we conceive is substance. The other acts, which have the first for their subject, are thought by us after the first and are called substantial in so far as they are altogether necessary to the subsistence of the first act. They are not necessary, however, to its concept (in their unity, they are called 'substantial form'). But in so far as they are not necessary, that is, in so far as they can in part vary without weakening substance or substantial acts, they are called accidental. They are accidental acts, or accidents. Added to these accidents are certain extrinsic determinations coming from reality, not from the idea of this ens.

841. The following, therefore, is the intrinsic order found in material ens by the understanding:

1. a first act, substance, without which the other acts are not understood, and to which is given the name ens;
2. acts, or substantial forms, which have for their subject the substance which dominates them, but which are necessary for the complete concept of this ens;
3. acts or accidental forms, which have for their subject substantial forms;
4. determinations not included in the full-specific idea of the ens, but coming from its reality.