St. Dionysios Areopagite [Διονύσιος ὁ Ἀρεοπαγίτης] distinguishes two possible theological ways. One — that of cataphatic or positive theology – proceeds by affirmations; the other — apophatic or negative theology by negations. The first leads us to some knowledge of God, but is an imperfect way. The perfect way, the only way which is fitting in regard to God, who is of His very nature unknowable, is the second — which leads us finally to total ignorance. All knowledge has as its object that which is. Now God is beyond all that exists. In order to approach Him it is necessary to deny all that is inferior to Him, that is to say, all that which is. If in seeing God one can know what one sees, then one has not seen God in Himself but something intelligible, something which is inferior to Him. It is by unknowing (αγνοία) that one may know Him who is above every possible object of knowledge. Proceeding by negations one ascends from the inferior degrees of being to the highest, by progressively setting aside all that can be known, in order to draw near to the Unknown in the darkness of absolute ignorance. For even as light, and especially abundance of light, renders darkness invisible; even so the knowledge of created things, and especially excess of knowledge, destroys the ignorance which is the only way by which one can attain to God in Himself.
—Vladimir Lossky (chapter 2 /The Divine Darkness/ Mystical Theology of the Eastern Church)