Caesar, who tries to fit the Gallic religion into the framework of Roman mythology—which was exactly what the Gauls themselves did after the conquest—says they held Mercury to be the chief of the gods, and looked upon him as the inventor of all the arts, as the presiding deity of commerce, and as the guardian of roads and guide of travellers. One may conjecture that he was particularly, to the Gauls as to the Romans, the guide of the dead, of travellers to the Other-world, Many bronze statues to Mercury, of Gaulish origin, still remain, the name being adopted by the Gauls, as many place-names still testify(70). Apollo was regarded as the deity of medicine and healing, Minerva was the initiator of arts and crafts, Jupiter governed the sky, and Mars presided over war. Cæsar is here, no doubt, classifying under five types and by Roman names a large number of Gallic divinities. *The God of the Underworld* According to Cæsar, a most notable deity of the Gauls was (in Roman nomenclature) Dis, or Pluto, the god of the Underworld inhabited by the dead. From him all the Gauls claimed to be descended, and on this account, says Cæsar, they began their reckoning of the twenty-four hours of the day with the oncoming of night.(71) The name of this deity is not given. D’Arbois de Jubainville considers that, together with Æsus, Teutates, Taranus, and, in Irish mythology, Balor and the Fomorians, he represents the powers of darkness, death, and evil, and Celtic mythology is thus interpreted as a variant of the universal solar myth, embodying the conception of the eternal conflict between Day and Night. *The God of Light* The God of Light appears in Gaul and in Ireland as Lugh, or Lugus, who has left his traces in many place-names such as _Lug-dunum_ (Leyden), Lyons, &c. Lugh appears in Irish legend with distinctly solar attributes. When he meets his army before the great conflict with the Fomorians, they feel, says the saga, as if they beheld the rising of the sun. Yet he is also, as we shall see, a god of the Underworld, belonging on the side of his mother Ethlinn, daughter of Balor, to the Powers of Darkness. *The Celtic Conception of Death*