the chariot should have four wheels, to correspond with the four elements or natures. The chariot as a spherical vessel and as consciousness rests on the four elements or basic functions
Jung establishes the chariot as an archetypal image of consciousness itself, its four wheels expressing the quaternity of psychic functions that orient the self to its environment.
, Mysterium Coniunctionis: An Inquiry into the Separation and Synthesis of Psychic Opposites in Alchemy, 1955thesis