αὐτὸν κέκρουκας τὸν βατῆρα τοῦ λόγου → you have struck the very threshold of the argument, you have struck the most important and chiefmost point
adj.
Of persons or things: P. and V. ἁπλοῦς; see free. Of things: P. and V. εὐθύς. Sheer, unmixed: P. ἄκρατος; see absolute. Downright slavery: P. ἄντικρυς (adv.) δουλεία (Thuc. 1, 122).