afterlife. Additionally, Ovid wrote that Mercury carried Morpheus' dreams from the valley of Somnus to sleeping humans. Archeological evidence from Pompeii suggests that Mercury was among the most popular of Roman gods. The god of commerce was depicted on two early bronze coins of the Roman Republic, the sextans and the . Syncretism When they described the gods of Celtic and Germanic tribes, rather than considering them separate deities, the Romans interpreted them as local manifestations or aspects of their own gods, a cultural trait called the . Mercury, in particular, was reported as becoming extremely popular among the nations the Roman Empire conquered; Julius Caesar wrote of Mercury being the most popular god in Britain and Gaul, regarded as the inventor of all the arts. This is probably because, in the Roman syncretism, Mercury was equated with the Celtic god Lugus, and in this aspect was commonly accompanied by the Celtic goddess Rosmerta. Although Lugus may originally have been a deity of light or the sun (though this is disputed), similar to the Roman Apollo, his importance as a god of trade made him more comparable to Mercury, and Apollo was instead equated with the Celtic deity Belenus. Romans associated Mercury with the Germanic god , by ; 1st-century Roman writer Tacitus identifies him as the chief god of the Germanic peoples. Names and epithets Mercury is known to the Romans as and occasionally in earlier writings as or , had a number of epithets representing different aspects or roles, or representing syncretisms with non-Roman deities. The most common and significant of these epithets included the following: Mercurius Artaios, a syncretism of Mercury with the Celtic god Artaios, a deity of bears and hunting who was worshiped at Beaucroissant, France. Mercurius Arvernus, a syncretism of the Celtic Arvernus with Mercury. Arvernus was worshiped in the Rhineland, possibly as a particular deity of the Arverni tribe, though no dedications to Mercurius Arvernus occur in their territory in the Auvergne region of central France. Mercurius Cimbrianus, a syncretism of Mercury with a god of the Cimbri sometimes thought to represent Odin. Mercurius Cissonius, a combination of Mercury with the Celtic god Cissonius, who is written of in the area spanning from Cologne, Germany to Saintes, France. Mercurius Esibraeus, a syncretism of the Iberian deity Esibraeus with the Roman deity Mercury. Esibraeus is mentioned only in an inscription found at Medelim, Portugal,