Plato's chariot allegory, found in the dialogue Phaedrus. Plato describes a charioteer who is trying to control two horses. One horse is a well behaved white steed, the other a troublesome, stubborn black steed. The charioteer represents the intellect and reason of our souls, the white horse represents the best of our passions, while the black horse represents the dark, dangerous aspects of our passions. The allegory ends up explaining how a soul incarnates.
I like to connect this card to the Jewish teaching of the good impulse (the yetzer ha-tov) and the evil impulse (the yetzer ha-ra). We all have both--and we all need both. The good impulse is our moral compass and moral sensitivity; the evil impulse is our ambition, willpower and chutzpah. The evil impulse is dangerous--if we don't strenuously regulate it, we become monsters. But without it, we'd never have the gumption to accomplish anything.
An old Star Trek episode--The Enemy Within--illustrates this. Kirk is split into two people, one exemplifying his yetzer ha-tov, and the other exemplifying his yetzer ha-ra. His 'good' side is benevolent and compassionate, but incable of making a decision or leading effectively. His 'evil' side is proactive and determined but a thorough bastard. See Sum of His Parts by David Holzel for a more detailed analysis of the episode and its (accidental?) relationship to the teaching of the good and evil impulse. (A nice Jewish boy like Shatner must have made the connection, right?)
The lesson I'm going to take from this card is to examine my characters and see how well each balances the two impulses. They'll be more intriguing, I suppose, if they haven't got the balance right . . .
But that's my take on The Chariot. As I said above, I've never seen a book that links it to Plato's chariot allegory. I've never seen a book that links it to the Jewish teaching of the good impulse and evil impulse either--although some have said essentially the same thing without mentioning the yetzer ha-tov and yetzer h-ra. But I'd like to hear other interpretations. What's your take on the card?