αὐτὸν κέκρουκας τὸν βατῆρα τοῦ λόγου → you have struck the very threshold of the argument, you have struck the most important and chiefmost point
căvillum: i, v. cavilla.
căvillum, ī, n., Apul. M. 1, 7, et căvillus, ī, m., Apul. M. 2, 19, c. cavilla.
cavillum u. cavillus, s. cavilla no. I.