“The alchemist saw the union of opposites under the symbol of the tree, and it is therefore not surprising that the unconscious of present-day man, who no longer feels at home in his world and can base his existence neither on the past that is no more nor on the future that is yet to be, should hark back to the symbol of the cosmic tree rooted in this world and growing up to heaven - the tree that is also man. In the history of symbols this tree is described as the way of life itself, a growing into that which eternally is and does not change; which springs from the union of opposites and, by its eternal presence, also makes that union possible. It seems as if it were only through an experience of symbolic reality that man, vainly seeking his own “existence” and making a philosophy out of it, can find his way back to a world in which he is no longer a stranger.”

― C.G. JungPsychological Types

The white bird is a half-celestial soul of man.
He abides with the mother, descending from time to time.
He is chaste and solitary, a messenger of the mother. He flies high above the earth.
He commands singleness. He brings knowledge from the distant ones, who have departed before and attained perfection.
He bears our word up to the mother. She intercedes, she warns, but she is powerless against the Gods.
She is a vessel of the sun.

The serpent descends and cunningly lames the phallic daimon, or else goads him on.
She bears up the too-crafty thoughts of the earthly, those thoughts that creep through every hole and cleave to all things with craving. Although the serpent does not want to, she must be of use to us.
She flees our grasp, thus showing us the way, which our human wits could not find.”

Carl Jung, Red Book, Page 353.