οὐ γὰρ πράξιν ἀγαθὴν, ἀλλὰ καὶ εὖ ποεῖν αὐτὴν → it does not suffice to do good–one must do it well
P. and V. ἱκανός, ἀρκῶν, P. διαρκής, V. ἐξαρκής.