Caduceus (Gr.). The Greek poets and mythologists took the idea of the Caduceus of Mercury from the Egyptians. The Caduceus is found as two serpents twisted round a rod, on Egyptian monuments built before Osiris. The Greeks altered this. We find it again in the hands of Æsculapius assuming a different form to the wand of Mercurius or Hermes. It is a cosmic, sidereal or astronomical, as well as a spiritual and even physiological symbol, its significance changing with its application. Metaphysically, the Caduceus represents the fall of primeval and primordial matter into gross terrestrial matter, the one Reality becoming Illusion. (See Sect.Doct. I. 550.) Astronomically, the head and tail represent the points of the ecliptic where the planets and even the sun and moon meet in close embrace. Physiologically, it is the symbol of the restoration of the equilibrium lost between Life, as a unit, and the currents of life performing various functions in the human body.
Source: H.P.Blavatsky - The Theosophical Glossary