Peh el peh, mouth to mouth, is the Torah's own phrase for the highest grade of prophetic communion. Numbers 12:8 sets it against everything else: with ordinary prophets HaShem speaks in visions, dreams, and riddles; "with My servant Moshe... peh el peh I speak with him, u-mar'eh, in clear seeing, v'lo b'chidot, and not in riddles." Exodus 33:11 says the same thing with faces: HaShem spoke to Moshe panim el panim, face to face, as a man speaks to his friend. Deuteronomy 34:10 closes the Torah on it: no prophet arose again in Israel like Moshe, whom HaShem knew face to face.

This is the phrase Sha'ul (Paul) is reaching back to in 1 Corinthians 13:12 when he contrasts our present mirror-grade seeing with "then, face to face." The hope of the New Covenant is not a clearer set of riddles. It is Jeremiah 31 carried to its end: Torah written on the lev, every covenant member knowing HaShem directly, the Moshe grade of speech no longer reserved for one servant on one mountain.