Man is dual: exterior and interior, flesh and spirit. […] Training, then, must also be twofold, outer and inner: outer in reading books, inner in thoughts of God; outer in love of wisdom, inner in love of God; outer in words, inner in prayer; outer in keenness of intellect, inner in warmth of spirit; outer in technique, inner in vision. The exterior mind is “puffed up,” the inner humbles itself; the exterior is full of curiosity, desiring to know all, the inner pays attention to itself and desires nothing other than to know God, speaking to Him as David spoke when he said, “my heart hath talked with thee” ‘seek ye my face’; ‘Thy face will I seek.” (St Dimitri of Rostov from The Art of Prayer: an Orthodox Anthology p. 44)
I found the above passage interesting because, while it makes a good deal of sense and is no doubt true, it does not follow our usual way of speaking about “inwardness.” Usually we would conflate his two meanings of outer and inner and add another outer-outer man. I suspect we would usually say, like Socrates in the Republic, that for the outer man there is gymnastics and fighting, and for the inner music and mathematics, or some similar combination of physical and intellectual activity. Church fathers, on the other hand, are often very precise about not conflating the intellect (the outer-inner man) and the heart/spirit (the inner-inner man). Generally we’re already familiar with the intellect — we probably wouldn’t be reading them at all if not, and the vast majority of education is aimed at the intellect — and talk about the heart, because that’s where we meet God. Something that I find to be quite interesting is that even the pagan ancients tended to locate the mind as much in the heart as in the head; even Lucretius with his strict materialism and Aristotle (so the notes say) do so. There is in Greek a kind of distinction between the mind of the head (intellect) and the mind of the heart (nous) — which encompasses a much greater meaning than just the emotions. The philosophers sometimes conflate intellect and nous (for Aristotle nous is “that which perceives first principles,” for instance), while the theologians are careful to distinguish them, as St. Dimitri does in the above passage.