But devotion is an act of the appetitive powers of the soul, and is, as we have said above, a movement of the will.
Cajetan: With regard to the proper meaning of the term devotion, note that since devotion is clearly derived from devoting, and since to devote—derived in its turn from to vow—means to promise something spontaneously to God: it follows that the principle in all such promises is the will; and further, not the will simply as such, but the will so affected as to be prompt. Hence in Latin those are said to be devoted to some superior whose will is so affected towards him as to make them prompt in his regard. And this seems to refer especially to God and to those who in a sense stand in His place, as, for instance, our rulers, our fatherland, and our principles of action. Hence in the Church's usage the term devotion is especially applied to those who are so affected towards God as to be prompt in His regard and in all that concerns Him. And so devotion is here taken to signify the act of a will so disposed, the act by which a man shows himself prompt in the Divine service.... Thus, then, devotion, the principal act of the virtue of religion, implies first of all the prompt desire of the Divine honour in our exercise of Divine worship; and hence comes the prompt choice of appropriate means to this end, and also the prompt carrying out of what we see to be suitable to that end. And the proof of possession of such devotion is that truly devout souls, the moment they perceive that some particular thing (or other) ought to be done for the service of God, are so promptly moved towards it that they rejoice in having to do or in actually doing it (on 2. 2. 82. 1).
S. Augustine: Give me, O Lord, Thyself; grant Thyself to me! For Thee do I love, and if my love be but weak, then would I love Thee more. For I cannot measure it so as to know how much my love falls short of that love which shall make my life run to Thy embraces nor ever turn away from Thee till I be hid in the hiding-place of Thy countenance. This only do I know: that it fares ill with me when away from Thee; and this not merely externally, but within me; for all abundance which is not my God is but penury for me! (Confessions, XIII. viii. 2).
II
Is Devotion an Act of the Virtue of Religion?
Devotion is derived from "devoting oneself" or making vows. But a vow is an act of the virtue of religion. Consequently devotion also is an act of the virtue of religion.
It belongs to the same virtue to wish to do a thing and to have a prompt will to do it, for the object of each of these acts is the same. For this reason the Philosopher says[82]: "Justice is that by which men will and perform just deeds." And it is clear that to perform those things which pertain to the Divine worship or service comes under the virtue of religion. Consequently it belongs to the same virtue of religion to have a prompt will to carry out these things—in other words, to be devout. Whence it follows that devotion is an act of the virtue of religion.
But some argue that devotion is not an act of the virtue of religion, thus:
1. Devotion means that a man gives himself to God. But this belongs to the virtue of charity, for, as S. Denis says[83]: "Divine love causes ecstasy since it permits not that those who love should belong any more to themselves, but to those things which they love." Whence devotion would seem to be rather an act of charity than of the virtue of religion.