Mercury, a son of Jupiter and the earth-goddess Maia, was born in a cave on Mount Cylbene in Arcadia, and closely resembles the Greek god Hermes. Like the latter, Mercury is accredited with the invention of the lyre from a tortoise shell, and with various misdemeanors including the theft of cattle of Apollo, an allegory on the blowing away of the clouds (Apollo's herds). Mercury also personified the wind. Apollo presented Mercury with the gift of a winged baton, the caduceus, which possessed the power for resolving conflicts and disputes. The gods also presented Mercury with winged sandals, or talaria, and cap, petasus; thus he became the messenger god.
Originally Mercury was god of riches but became the patron of travelers and thieves. He was introduced in the Roman pantheon toward the end of the fifth century, after Rome had expelled the Tarquins and felt the need for good deities who would assure good harvests and prosperous trading. His temple on Aventine Hill first became the center of the corn trade, and eventually trade in general. His main festival, the Mercuralia, took place on the Ides of May, and his statures, usually with the symbols of Hermes, were frequently placed as boundary markers.
As Psychopompus Mercury leads the souls of the dead into Hades, and as Oneicopompus he oversees the world of dreams. A.G.H.
Grimal, Pierre, Larousse World Mythology, Secaucus, New Jersey, Chartwell Books, 1965, p. 180
Jordan, Michael, Encyclopedia of Gods, New York, Facts On File, Inc. 1993, p. 163