γέλως ἄκαιρος κλαυμάτων παραίτιος → ill-timed laughter causes tears (Menander)
careless: P. and V. ῥᾴθυμος.
light-minded: V. κουφόνους.
fickle: P. and V. ἔμπληκτος.
now are you flighty and your wisdom is as folly: V. νῦν γὰρ πέτει τε καὶ φρονῶν οὐδὲν φρονεῖς (Eur., bacch. 332).