αὐτὸν κέκρουκας τὸν βατῆρα τοῦ λόγου → you have struck the very threshold of the argument, you have struck the most important and chiefmost point
P. and V. λάλος, P. πολύλογος, V. στόμαργος, πολύγλωσσος, ἀθυρόγλωσσος, Ar. λαλητικός.