Swift footed, Mercury (known to Greeks as Hermes), the messenger of Jupiter and herald to the gods, was the patron deity of travelers, gamblers, tricksters, and businessmen. To him is ascribed the introduction of deploying embassies in the capitals of foreign empires in order to broker peace through diplomatic channels instead of war. Mercury, the robber and cattle driver, the prince of thieves at the gates, the bringer of dreams, the patron of travelers, is also credited with assisting the Fates during the creation of the alphabet, securing his role as the governor of the tongue and the guide of intelligent speech. He also invented the lyre from a tortoise shell and gave this musical instrument to Apollo who, in turn, gave Mercury a caduceus, the golden staff crowned by wings and intertwined with serpents--symbol of today's medical profession. Mercury is sometimes called Argiphontes, for having killed the all-seeing Argos I who guarded Io. He is also referred to as Psychopompus in the context of his role as the guide of the souls of the deceased to the Underworld.