Chapter 2

Summary of the distinction between potencies and their acts

942. The soul's term can undergo change or modification from two sources: from the principle which is the essence of the soul, and from a cause different from the soul. This change can be conceived in different ways: 1. the term is completely divided from its principle, in which case it is no longer term; 2. one term is removed and another, specifically different term substituted; here, the essence of the soul is changed; the soul ceases to be what it was; 3. the term is specifically increased, in which case the essence of the soul, although increased, remains the same (cf. 184-199).
I will pass over these conceivable changes to speak about those which can not only be conceived but, as experience attests, occur every day.

943. The following can be said about these changes:

1. The soul's term is partly constant and invariable; it specifies the human soul and determines its nature. The invariable part is twofold, being a) an extended felt element that contains a continual change of parts causing the feeling of stimulation and a determinate organism; and b) indeterminate, ideal being.

2. The soul's term is partly variable. Relative to the body, this variability consists in extension and intestine movement, which is the cause of the stimulation and the organism, and of perpetuity of life. Relative to ideal being (not subject to change), variability is only in the soul in so far as the soul sees in being the real things perceived in sense, and extracts from them the doctrine of reality. Thus its object is enriched without change to itself, because the soul sees in its object that which it did not see previously.

All these changes give rise to accidental acts which, when they cease, leave habits in the soul.

944. Accidental acts arise therefore through the changes which take place in the terms of the soul, without the terms changing specifically. The changes take place either in virtue of the activity proper to the soul, in which case they are active acts, or in virtue of a cause foreign to the soul, in which case they are passive acts.

Habits arise from the traces of activity remaining in the soul when accidental acts cease.

Finally, potencies arise from the specific diversity of the terms joined to activity of the soul.