The caduceus is the winged staff of Hermes (Mercury), which gave the god the power to fly. Originally a simple olive branch, its stems were afterwards formed into snakes, and several poetical tales devised by the mythologists to explain this, as that Hermes having found two snakes fighting, divided them with his rod, and thus they came to be used as an emblem of peace. It was the staff or mace carried by heralds and ambassadors in time of war. It was not used by the Romans. Many magical virtues were ascribed to the caduceus; in Homer, Hermes touches with it the souls of the dead, and so lulls them to sleep before carrying them to the underworld. It is also seen in the hands of Ares (Mars), Dionysius, Hercules, Demeter, and Aphrodite.