http://en.wikipedia.org/wiki/Whom_the_gods_would_destroy

"Whom the gods would destroy, they first make mad" (Latin: Quem deus vult perdere, dementat prius) appeared originally in the Greek play Medea by Euripides[1], the play describes Medea's descent (and her awareness of this descent as it occurs) into self destructive madness where she kills her own children in order to hurt her ex lover.