μὴ κακὸν εὖ ἔρξῃς· σπείρειν ἴσον ἔστ' ἐνὶ πόντῳ → do no good to a bad man; it is like sowing in the sea
P. and V. ὀξύς, νεανικός, P. προπετής, σφοδρός.