The Red Book (Philemon)

Apart from Elijah and Salome I found the serpent as a third principle.

It is a stranger to both principles although it is associated with both.

The serpent taught me the unconditional difference in essence between the two principles in me.

If I look across from forethinking to pleasure, I first see the deterrent poisonous serpent.

If I feel from pleasure across to forethinking, likewise I feel first the cold cruel serpent.

The serpent is the earthly essence of man of which he is not conscious.

Its character changes according to peoples and lands, since it is the mystery that flows to him from the nourishing earth-mother.
~Carl Jung, The Red Book.