Lucan mentions a god Esus, who is represented on a Paris altar as a woodman cutting down a tree, the branches of which are carried round to the next side of the altar, on which is represented a bull with three cranes—Tarvos Trigaranos. The same figure, unnamed, occurs on another altar at Trèves, but in this case the bull's head appears in the branches, and on them sit the birds. M. Reinach applies one formula to the subjects of these altars—"The divine Woodman hews the Tree of the Bull with Three Cranes."58 The whole represents some myth unknown to us, but M. D'Arbois finds in it some allusion to events in the Cúchulainn saga. To this we shall return.59 Bull and tree are perhaps both divine, and if the animal, like the images of the divine bull, is three-horned, then the three cranes (garanus, "crane") may be a rebus for three-horned (trikeras), or more probably three-headed (trikarenos).60 In this case woodman, tree, and bull might all be representatives of a god of vegetation. In early ritual, human, animal, or arboreal representatives of the god were periodically destroyed to ensure fertility, but when the god became separated from these representatives, the destruction or slaying was regarded as a sacrifice to the god, and myths arose telling how he had once slain the animal. In this case, tree and bull, really identical, would be mythically regarded as destroyed by the god whom they had once represented. If Esus was a god of vegetation, once represented by a tree, this would explain why, as the scholiast on Lucan relates, human sacrifices to Esus were suspended from a tree. Esus was worshipped at Paris and at Trèves; a coin with the name Æsus was found in England; and personal names like Esugenos, "son of Esus," and Esunertus, "he who has the strength of Esus," occur in England, France, and Switzerland.61 Thus the cult of this god may have been comparatively widespread. But there is no evidence that he was a Celtic Jehovah or a member, with Teutates and Taranis, of a pan-Celtic triad, or that this triad, introduced by Gauls, was not accepted by the Druids.62 Had such a great triad existed, some instance of the occurrence of the three names on one inscription would certainly have been found. Lucan does not refer to the gods as a triad, nor as gods of all the Celts, or even of one tribe. He lays stress merely on the fact that they were worshipped with human sacrifice, and they were apparently more or less well-known local gods.63
The insular Celts believed that some of their gods lived on or in hills. We do not know whether such a belief was entertained by the Gauls, though some of their deities were worshipped on hills, like the Puy de Dôme. There is also evidence of mountain worship among them. One inscription runs, "To the Mountains"; a god of the Pennine Alps, Poeninus, was equated with Juppiter; and the god of the Vosges mountains was called Vosegus, perhaps still surviving in the giant supposed to haunt them.64
Certain grouped gods, Dii Casses, were worshipped by Celts on the right bank of the Rhine, but nothing is known regarding their functions, unless they were road gods. The name means "beautiful" or "pleasant," and Cassi appears in personal and tribal names, and also in Cassiterides, an early name of Britain, perhaps signifying that the new lands were "more beautiful" than those the Celts had left. When tin was discovered in Britain, the Mediterranean traders called it (chassiteros), after the name of the place where it was found, as cupreus, "copper," was so called from Cyprus.65
Many local tutelar divinities were also worshipped. When a new settlement was founded, it was placed under the protection of a tribal god, or the name of some divinised river on whose banks the village was placed, passed to the village itself, and the divinity became its protector. Thus Dea Bibracte, Nemausus, and Vasio were tutelar divinities of Bibracte, Nimes, and Vaison. Other places were called after Belenos, or a group of divinities, usually the Matres with a local epithet, watched over a certain district.66 The founding of a town was celebrated in an annual festival, with sacrifices and libations to the protecting deity, a practice combated by S. Eloi in the eighth century. But the custom of associating a divinity with a town or region was a great help to patriotism. Those who fought for their homes felt that they were fighting for their gods, who also fought on their side. Several inscriptions, "To the genius of the place," occur in Britain, and there are a few traces of tutelar gods in Irish texts, but generally local saints had taken their place.
The Celtic cult of goddesses took two forms, that of individual and that of grouped goddesses, the latter much more numerous than the grouped gods. Individual goddesses were worshipped as consorts of gods, or as separate personalities, and in the latter case the cult was sometimes far extended. Still more popular was the cult of grouped goddesses. Of these the Matres, like some individual goddesses, were probably early Earth-mothers, and since the primitive fertility-cults included all that might then be summed up as "civilisation," such goddesses had already many functions, and might the more readily become divinities of special crafts or even of war. Many individual goddesses are known only by their names, and were of a purely local character.67 Some local goddesses with different names but similar functions are equated with the same Roman goddess; others were never so equated.
The Celtic Minerva, or the goddesses equated with her, "taught the elements of industry and the arts,"68 and is thus the equivalent of the Irish Brigit. Her functions are in keeping with the position of woman as the first civiliser—discovering agriculture, spinning, the art of pottery, etc. During this period goddesses were chiefly worshipped, and though the Celts had long outgrown this primitive stage, such culture-goddesses still retained their importance. A goddess equated with Minerva in Southern France and Britain is Belisama, perhaps from qval, "to burn" or "shine."69 Hence she may have been associated with a cult of fire, like Brigit and like another goddess Sul, equated with Minerva at Bath and in Hesse, and in whose temple perpetual fires burned.70 She was also a goddess of hot springs. Belisama gave her name to the Mersey,71 and many goddesses in Celtic myth are associated with rivers.
Some war-goddesses are associated with Mars—Nemetona (in Britain and Germany), perhaps the same as the Irish Nemon, and Cathubodua, identical with the Irish war-goddess Badb-catha, "battle-crow," who tore the bodies of the slain.72 Another goddess Andrasta, "invincible," perhaps the same as the Andarta of the Voconces, was worshipped by the people of Boudicca with human sacrifices, like the native Bellona of the Scordisci.73
A goddess of the chase was identified with Artemis in Galatia, where she had a priestess Camma, and also in the west. At the feast of the Galatian goddess dogs were crowned with flowers, her worshippers feasted and a sacrifice was made to her, feast and sacrifice being provided out of money laid aside for every animal taken in the chase.74 Other goddesses were equated with Diana, and one of her statues was destroyed in Christian times at Trèves.75