On the Making of Man by Gregory of Nyssa — Read

What then is, in its own nature, this mind that distributes itself into faculties of sensation, and duly receives, by means of each, the knowledge of things? That it is something else besides the senses, I suppose no reasonable man doubts; for if it were identical with sense, it would reduce the proper character of the operations carried on by sense to one, on the ground that it is itself simple, and that in what is simple no diversity is to be found. Now however, as all agree that touch is one thing and smell another, and as the rest of the senses are in like manner so situated with regard to each other as to exclude intercommunion or mixture, we must surely suppose, since the mind is duly present in each case, that it is something else besides the sensitive nature, so that no variation may attach to a thing intelligible.

"Who hath known the mind of the Lord? " the apostle asks; and I ask further, who has understood his own mind? Let those tell us who consider the nature of God to be within their comprehension, whether they understand themselves -- if they know the nature of their own mind. "It is manifold and much compounded. " How then can that which is intelligible be composite? or what is the mode of mixture of things that differ in kind? Or, "It is simple, and incomposite. " How then is it dispersed into the manifold divisions of the senses? how is there diversity in unity? how is unity maintained in diversity?