Caduceus
The Staff of Hermes
The snakes are not in the Homeric Hymn to Hermes, where Apollo's gift is a golden staff. Macrobius (fifth century CE) reports the Egyptians shaped it as two serpents, male and female.
Homeric Hymn to Hermes ll. 521–549 (Evelyn-White, 1914); Macrobius, Saturnalia 1.19.16
A winged staff entwined by two serpents, carried by the Greek god Hermes.
More context
The caduceus is the herald's staff of Hermes, messenger of the gods, guide of the dead and patron of merchants. In the Homeric Hymn to Hermes, Apollo gives him a golden staff with three branches. Macrobius, early in the fifth century CE, describes two serpents knotted at the middle, their heads meeting in a kiss, with wings at the top. He reports that the Egyptians made the serpents male and female and read the staff as the sun. In 1927 the Theosophist C. W. Leadbeater made the staff the spine and the snakes the serpent-fire. Its use for medicine is a modern confusion with the rod of Asclepius.
Light
Facilitates clear communication, diplomatic resolution of conflicts, and the harmonious integration of opposing forces.
Shadow
Can imply manipulation, deceit in commerce, or the dangerous misuse of esoteric knowledge and communication for selfish ends.