In Jason and Theseus we have two heroes who enjoy an outstanding beginning and must suffer a tragic middle age. It is interesting how the magical and the realistic combine in many heroic legends. Often a hero's success is due to supernatural aid. Jason could have accomplished nothing without Medea's sorcery and Hera's protection. Yet an actual personality reveals itself in the legend. Jason seems bland, obliging, competent, guided solely by ambition. An effective organizer, he supervises the Argo expedition, but the ultimate purpose of the quest for the fleece is merely to establish his right to rule Pelias' kingdom. It is a right that he never obtains, because Medea takes revenge upon Pelias and they have to leave Iolcos. He then determines to rule Corinth by marrying the king's daughter, a move that brings down Medea's wrath on his head. He gains Corinth but loses his own soul, in effect, and the same ambition that guides his one great adventure ruins him in the end. The legend for all its fantastic elements is psychologically truthful.
The same holds good for Theseus, who is a different type entirely. Whereas Jason is self-serving, Theseus' great exploits prove beneficial to others. In ridding the land route to Athens of robbers he makes the way safe for other travelers. In killing the Minotaur he frees Athens of its obligatory human sacrifices. In giving Athens a democratic government he makes citizens out of subjects. Theseus makes a point of defending the weak. He is one hero who consciously models himself upon another—the great Heracles. If he lacks Heracles' sheer masculine exuberance, he is more intelligent than his model and his deeds have more point to them.
Generous, brave, helpful, and intelligent, Theseus still has flaws that undermine his happiness and bring his life to a sad end. For one thing, he has a streak of rashness that harms him. In abandoning Ariadne he seems to lay a curse on all his marital attachments. He wreaks his son's destruction through angry ignorance. He nearly perishes when he goes down to the underworld to abduct Persephone. And his negligence in failing to hoist the white sail sends his father Aegeus hurtling from a cliff, a fact that may have determined the manner of his own death, since he too dies in such a fall.
The Greeks understood character in a way that other cultures failed to penetrate. They grasped how a trait like ambition could turn from a virtue into a bane, and how a noble personality might have serious defects that lead to ruin. They regarded the exploits of Jason and Theseus as worthy of emulation, but they also knew that a price had to be paid for heroism, and they did not flinch at showing that price in these legends.
