I'm not sure why I didn't post about this a long time ago, but a friend interested in patristic/Orthodox epistemology got me to thinking about it again and I thought the time had come. Back before our Greek sojourn (so, ten years ago or so now), when I was reading through the Corpus Dionysiacum, I became fascinated with the following passage from the Divine Names 7.2:
The intelligent and intelligible powers of the angelic minds draw from Wisdom their simple and blessed conceptions. They do not draw together their knowledge of God from fragments nor from bouts of perception or of discursive reasoning. And at the same time, they are not limited to perception and reason. Being free from all burden of matter and multiplicity, they think the thoughts of the divine realm intelligently, immaterially, and in a single act. Theirs is an intelligent power and energy, glittering in an unmixed and undefiled purity, and it surveys the divine conceptions in an indivisible, immaterial, and godlike oneness. They become shaped as close as possible to the transcendently wise mind and reason of God, and this happens through the workings of the divine Wisdom.Human souls also possess reason and with it they circle in discourse around the truth of things. Because of the fragmentary and varied nature of their many activities they are on a lower level than the unified intelligences. Nevertheless, on account of the manner in which they are capable of concentrating the many into the one, they too, in their own fashion and as far as they can, are worthy of conceptions like those of the angles. Our sense perceptions also can properly be described as echoes of wisdom, and even the intelligence of demons, to the extent that it is intelligence, comes from it, though we could more accurately describe this as a falling away from wisdom, since demonic intelligence stupidly has no idea how to obtain what it really wants and indeed does not want it. 
I was reminded of this distinction between 'intelligence' and 'discursive reason' around the same time when I read one of Victor Watts's notes on Boethius's De consolatione 5.pr4: 
'Intelligence' (Latin intelligentia) in this passage bears a technical sense related to the two faculties which the rational soul was supposed to exercise, 'intellect' (intellectus) and 'reason' (ratio). 'Intellect' here means 'understanding' and is that imperfect faculty in corporeal man which corresponds to the perfect 'intelligence' of incorporeal angels: its relation to 'reason' is explained by St Thomas Aquinas (Ia, lxxxix, art. 8) as follows (quoted from The Discarded Image, p. 157): 'intellect (intelligere) is the simple (i.e., indivisible, uncompounded) grasp of an intelligible truth, whereas reasoning (ratiocinari) is the progression towards an intelligible truth by going from one understood point to another. The difference between them is thus like the difference between rest and motion or between possession and acquisition.' 
Watts then continues quoting C.S. Lewis's own words from the same passage in Discarded Image:
We are enjoying intellectus when we 'just see' a self-evident truth; we are exercising ratio when we proceed step by step to prove a truth which is not self-evident. A cognitive life in which all truth can be simply 'seen' would be the life of an intelligentia, an angel. A life of unmitigated ratio where nothing was simply 'seen' and all had to be proved, would presumably be impossible; for nothing can be proved if nothing is self-evident. Man's mental life is spent in laboriously connecting those frequent, but momentary, flashes of intelligentia which constitute intellectus. 
Although I can't comment on what common sources St Dionysius and Boethius might have drawn on for this distinction (except to suppose they must have been Platonic), it is of course not the least bit surprising that there is such a striking similarity between the Dionysian passage and that from Thomas Aquinas. Even someone so ignorant of Aquinas as I am well-appraised of the latter's indebtedness to the former throughout his work. My question is, assuming an Orthodox interpretation of St Dionysius--like that of Bishop-elect Alexander (Golitzin)--can Aquinas be found to have departed from his Master in his conception of intelligentia/intellectus? For me it's hard to see how such a doctrine can be supported apart from the robust conception of the 'divine energeia of the Holy Trinity' developed by St Gregory Palamas but, according to Fr Alexander, 'already present in the Areopagite'.  Certainly, in Lewis's explanation this type of knowledge sounds much more 'intellectual' in our modern sense than it does in St Dionysius. Anyway, I realise I'm departing from my area of expertise by even raising such a profoundly theological issue, but I felt that the juxtaposition of these texts rather demanded it! More importantly, I've recently found the distinction to be a useful one in the course of discussion with a friend who has from time to time posed questions about the ultimate nature of faith itself.
 St Dionysius the Areopagite, The Complete Works, trans. Colm Luibheid (NY: Paulist, 1987), pp. 106-7 .
 The passage from Boethius actually provides an interesting description of the difference between intelligentia and ratio as well: 'Reason transcends imagination, too, and with a universal consideration reflects upon the species inherent in individual instances. But there exists the more exalted eye of intelligence which passes beyond the sphere of the universe to behold the simple form itself with the pure vision of the mind' (Victor Watts, tr., The Consolation of Philosophy, by Boethius, rev. ed. [London: Penguin, 1999], p. 126).
 Ibid., p. 126, n. 5. I haven't yet tried to look through my own various translations of selections from Aquinas to find this passage. To tell the truth, I'm a little bit daunted by the prospect of finding any particular passage in him at all.
 C.S. Lewis, The Discarded Image: An Introduction to Medieval & Renaissance Literature (Cambridge: Cambridge U, 2002), p. 157.
 Archimandrite Alexander (Golitzin), 'Dionysius Areopagites in the Works of Saint Gregory Palamas: On the Question of a "Christological Corrective" & Related Matters', [see section III.A].