From St Thomas
Summa Theologica:
Whether adoration denotes an action of the body? IIa IIae q. 84 a. 2
Objection 1. It would seem that adoration does not
denote an act of the body. It is written (Jn. 4:23): “The
true adorers shall adore the Father in spirit and in truth.”
Now what is done in spirit has nothing to do with an act
of the body. Therefore adoration does not denote an act of
the body.

Objection 2. Further, the word adoration is taken
from “oratio” [prayer]. But prayer consists chiefly in an
interior act, according to 1 Cor. 14:15, “I will pray with
the spirit, I will pray also with the understanding.” Therefore
adoration denotes chiefly a spiritual act.

Objection 3. Further, acts of the body pertain to sensible
knowledge: whereas we approach God not by bodily
but by spiritual sense. Therefore adoration does not denote
an act of the body.

On the contrary, A gloss on Ex. 20:5, “Thou shalt
not adore them, nor serve them,” says: “Thou shalt neither
worship them in mind, nor adore them outwardly.”
I answer that, As Damascene says (De Fide Orth. iv,
12), since we are composed of a twofold nature, intellectual
and sensible, we offer God a twofold adoration;
namely, a spiritual adoration, consisting in the internal devotion
of the mind; and a bodily adoration, which consists
in an exterior humbling of the body. And since in all acts
of latria that which is without is referred to that which is
within as being of greater import, it follows that exterior
adoration is offered on account of interior adoration, in
other words we exhibit signs of humility in our bodies in
order to incite our affections to submit to God, since it is
connatural to us to proceed from the sensible to the intelligible.
Reply to Objection 1. Even bodily adoration is done
in spirit, in so far as it proceeds from and is directed to
spiritual devotion.

Reply to Objection 2. Just as prayer is primarily in
the mind, and secondarily expressed in words, as stated
above (q. 83, a. 12), so too adoration consists chiefly in
an interior reverence of God, but secondarily in certain
bodily signs of humility; thus when we genuflect we signify
our weakness in comparison with God, and when we
prostrate ourselves we profess that we are nothing of ourselves.

Reply to Objection 3. Though we cannot reach God
with the senses, our mind is urged by sensible signs to
approach God.

The “Summa Theologica” of St. Thomas Aquinas. Literally translated by Fathers of the English
Dominican Province. Second and Revised Edition, 1920.