Noesis refers to immediate, intuitive understanding or insight, while dianoia involves discursive thinking, particularly in mathematical and technical contexts. Essentially, noesis is about direct apprehension, whereas dianoia is a more analytical and reasoned thought process.

In the Christian Latin West, the Enlightenment (17th – early 19th century) enthroned and focused almost entirely on the discursive, analytical, reasoning mind. So complete was that focus on the sensory, reasoning faculty (dianoia), that it literally came to define “mind” in the Western world. It still does.

The Greek East, although influenced heavily by the Enlightenment, did not lose their ancient distinction between noesis, direct apprehension, and dianoia, reasoned thought. To them, mind was “nous” (a term unknown in the West), and included both the noetic and the dianoetic faculties of the human mind.

In Eastern Christian culture, the noetic faculty is considered more mature than the dianoetic, because by noesis humans can instantly and intuitively apprehend God and truth of things spiritual whereas dianoia is focused on a dualistic understanding of the material, sensory world. It is no accident that noesis and dianoia both share the same Greek root; nous.

So, I guess one could say that both the Latin West and Greek East defined “mind” correctly; the West just lost the better half of theirs.