Like many of Euripides' tragedies, Herakles consists of two parts. Having been raised to the height of triumph when he kills Lycus, Herakles is then driven to the depths of despair by Madness. There is no real connection between the two parts, and for this reason, the play is often criticized for lack of unity.
Courage, endurance and nobility are the themes of this play. Megara in the first half of the play and Herakles in the second are innocent victims of powerful, authoritative forces they cannot defeat. The spiteful, irrational nature of Hera's jealous plot against Herakles can be seen to mirror Euripides' notion of an indifferent world ruled by chance. Herakles' reactions also carry a message for men to rely on themselves, not on the hope of divine authority and wisdom—that the concept of moral goodness operates in humanity alone. Herakles must learn to recognise and live with the fact that violence and madness are part of his nature and only he has the right to forgive what he has done.