The arcana of the (7) Chariot is associated with water although the watery element is only hinted at in the wavelike formation of the blue canopy of the chariot in the Morgan-Greer rendering which we are using for our daily readings. More traditional images depict the beasts that pull the chariot as sphinxes rather than horses, and the sphinxes are stationary. They are, like the horses in the Morgan-Greer illustration, black and white, which remind us of the pillars of Jachin and Boas between which the (2) High Priestess is seated.
Once in motion, the two beasts, which represent contrary energies, would automatically pull in opposite directions were it not for the harness and chariot pole that keeps them together and converts their positive and negative energies into forward motion thanks to the skill of the charioteer. Speaking of the (7) Chariot in The Tarot of the Magicians Oswald Wirth comments,
It is a question of the fixing of ‘Mercury of the Wise’ an operation accomplished by Hermes when, placing his wand between two serpents struggling to devour each other, he brought about the formation of the Caduceus. The mission of directing intelligence is to reconcile basic opposing factors.The Tarot of the Magicians, p. 91
Thus, we are presented with a model for the psyche in which we do not repress the dark side in order to accentuate the light, but rather acknowledge that it exists so as to harness its energy to achieve a healthy balance and movement in our lives. The message of the (7) Chariot in conjuction with the Six and the Knight of Pentacles is to stay in touch with the earthy and subterranean aspects of our soul, not to reify it into egotistical or idolatrous structures such as the (16) Tower of Destruction, but rather to achieve a balance and harmony in our dealings in the outer as well as the inner world, so that we may in turn realize the ideal of the pre-existent harmony,
as above, so below.