The Works of Dionysius the Areopagite, tr. by John Parker, [1897], at sacred-texts.com

LETTER III. To the same Gaius.

"Sudden" is that which, contrary to expectation, and out of the, as yet, unmanifest, is brought into the manifest. But with regard to Christ’s love of man, I think that the Word of God suggests even this, that the Superessential proceeded forth out of the hidden, into the manifestation amongst us, by having taken substance as man. But, He is hidden, even after the manifestation, or to speak more divinely, even in the manifestation, for in truth this of Jesus has been kept hidden, and the mystery with respect to Him has been reached by no word nor mind, but even when spoken, remains unsaid, and when conceived unknown. p. 143