Another Facebook wall response that should be saved somewhere….
Someone flagged me on this question: “Serious question for 'theologians' of sorts (since all of my books are all packed up currently). My question is this: Is there a Thomistic equivalent of the 'nous' as used and understood by the Eastern Fathers?”
My response:
Glory to Jesus Christ!
This is a great question. I had a conversation with a wise Dominican recently. We were discussing other matters when this topic came up in passing. He confirmed what I have thought (and... what I have taught if it comes up in class): the notion of _nous_, which you're going to find used in various ways, covers a number of phenomena in the Scholastic lexicon.
The quasi-generic meaning of "nous" is, as others above have noted, an ability (and its related act) to know in a direct manner, without an intrinsic mediation of a discursus.
For this reason, as some said above, _intellectus_, insight into first principles (a natural-intellect capacity) fills this role. (There is a role, however, for extrinsic, dialectical reasoning to enable this kind of direct insight.)
However, even here at the level of nature there is also the ability to know defined wholes (the work of the "first operation of the intellect"). Fr. Garrigou-Lagrange, citing Aristotle, emphasizes in several places how this is the work of "nous". (Fr. Boncenski also provided RGL with some further backup for this claim.) Fr. Garrigou very often emphasized the need to pay heed to defining of terms. Even if this risks a "conceptualism", the point also helps to prevent discursive rationality from formalizing philosophy and theology. (I prefer not here getting into the whole "conceptualism" issue. It's just too detailed for a Facebook discussion.. - Says the man who is writing a huge response!) Note, also, that extrinsic reasoning comes to bear here. (Think of the way that the predicables—which pertain to second intentions formed by the first operation of the intellect—are discussed in the dialectics of the _Topics_.)
So, up to now, we have been at the level of "nature". Knowledge through the first and second operations of the intellect are primarily direct, even if they might involve dialectical reasoning (in order to clear the underbrush so that the phenomenon in question might stand forth). Thus, we are speaking of: defining and _intellectus_.
You'll find this sort of language at times in Eastern authors.
But….!
Another important strand—and the one that is most important in the end—will really be speaking in the register of the supernatural order.
(Aside: Do not listen to those who say that distinctions between nature and grace cannot be found in the East. There are various ways that this is articulated, but by the time of Maximus and quite powerfully in Palamas, you'll find it with striking clarity. Obviously, we must not read Latin problematics on to them. But, it makes total sense that St. Gregory needed to articulate this in the controversies over grace and divinization.)
Here, the Thomist position on faith, which is not discursive, is built on a kind of super-analogy (cf. Journet, Nicolas, Maritain, and even implicitly Garrigou) with _intellectus_. Our knowledge through faith is direct knowledge, elicited in the supernatural light of the truthfulness of God who reveals (and who gives us the subjective capacity for eliciting such an act of supernatural knowledge). This faith-knowledge is also sometimes what falls under _nous_ in Eastern authors.
But, even more, to the degree that such Eastern Spiritual texts push toward the apophatic, experiential (or quasi-experiential, as the Thomist in me would say...), it seems clear to my eyes that _nous_ is there used in the sense of the Thomist notion of the gifts of understanding, perhaps knowledge, and indeed wisdom—all which are a perfecting of faith, the latter being mediated through the love of charity in a unique way that is the most quasi-unmediated in character. (We "taste" the mysteries through the mediation of God active as the vivifying principle of our supernatural life.) The issue of the mediation of this knowledge should be read in light of Gardeil's _La Structure...._ and the important debates / discussions that followed upon it.
Finally (and actually connected with Gardeil's work in fact), we have something related to the Augustinian notion of _mens_: the spiritual heights of the soul; the soul as mind, not as soul. (This represents, on the level of substance-constitutive, a parallel to the intellect as intellect and the intellect as rational.) This would be the height of the soul as the "insertion point" for grace (or "toothing stone" expecting it, as some would say this - both metaphors have their dangers, but metaphors help us grope toward truth—just remember that for the strict Thomists, the "toothing stone" is a negative obediential potency). In any case, this sense of _nous_ would be _the spiritual heights of the soul, that part of us which is first divinized by grace, and from which will flow all the radiation of grace over the rest of the "organism"_.
So.... In sum....
_Nous_ is going to cover:
In the order of nature:
Acts of the first "operation" of the intellect in defining notions.
Acts of the second "operation" of the intellect, in particular first principles grasped through _intellectus_ and _synderesis_
We might perhaps add to this, as well, "Intellectus" in the moral order of particular truths. (See the virtues annexed to prudence.)
There would also likely be here poetic knowledge, somewhat like what Maritain describes.
Then, in the order of grace:
Our foundational capacity, as spirit, for the reception of grace ("obediential potency", or _mens_)
Faith
Then the contemplative gifts of the Holy Spirit (understanding, knowledge, and wisdom), in particular wisdom
Whew……
Addendum:
I should add, that the "active intellect" is also important behind a number of these aforementioned groupings. It would be useful to read Gilson's (still in French, I think) article on Aquinas's development of the notion. The "active intellect" is the spiritually highest point of the intellect's actuality in the order of nature. Thus, it, along with _soul-as-mens_ will be the best parallel for _nous_