The caduceus (kerykeion in Greek) was herald’s staff with two snakes wound around it. It was carried by Hermes to signify his role as messenger and as guide for souls to the Underworld. Hermes can sometimes use the caduceus as a way to channel the power he has, such as waking or putting mortals to sleep [Homer, Iliad, 24.343-345]. It should be carefully distinguished from the rod of Asclepius, which had only one snake, which Asclepius used in healing.
Mythology Unbound: An Online Textbook for Classical Mythology by Jessica Mellenthin and Susan O. Shapiro is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.