John of Damascus on mystery and manifestation

Recently I have been revisiting some work by former Anglican Primate Peter Carnely. He appeals to the Fathers in his insistence that 'mystery' and not 'manifestation' is the right category to think about God. But it's a false dichtomy, and a read of the Fathers shows that they knew it was too. God is, as Scripture says, unknown to us in his essence, but at the same time, self-revealing. This from John of Damascus seems utterly contrary to Carnley (who is really channeling HL Mansel's Kantian ramblings from the latter part of the 19th century):

…neither do we know, nor can we tell, what the essence of God is, or how it is in all, or how the Only-begotten Son and God, having emptied himself, became Man of virgin blood, made by another law contrary to nature, or how He walked with dry feet upon the waters. It is not within our capacity, therefore, to say anything about God or even to think of Him, beyond the things which have been divinely revealed to us, whether by word of by manifestation, by the divine oracles at once of the Old Testament and of the New.

Exposition of the Orthodox Faith I.2