apophasis
From LSJ
αὐτὸν κέκρουκας τὸν βατῆρα τοῦ λόγου → you have struck the very threshold of the argument, you have struck the most important and chiefmost point
ăpŏphăsis: is, f., = ἀπόφασις> (denial), rhet. fig.,
I whereby one, as it were, answers himself, Jul. Rufin. 8.
