Δὶς ἐξαμαρτεῖν ταὐτὸν οὐκ ἀνδρὸς σοφοῦ → Qui sapit, eundem non bis errabit modum → Den selben Fehler zwei Mal macht kein kluger Mann
As opposed to really, in fact: use P. and V. λόγῳ, λόγῳ μέν.