μηδενὶ συμφορὰν ὀνειδίσῃς, κοινὴ γὰρ ἡ τύχη καὶ τὸ μέλλον ἀόρατον → never mock a disaster, fate is common to all and the future unknown
P. and V. ἄβουλος, ἀσύνετος, Ar. and P. ἀνόητος; see foolish.
off one's guard: P. and V. ἀφύλακτος.