Gaulish Dis Pater
In Book 6 of his Commentaries on the Gallic War, Julius Caesar refers to a Gaulish god whom the druids believed that all the Gauls were descended from. He does not give this god's name, but refers to him under the name of a Roman god he deemed comparable: Dis Pater, Roman god of prosperity and of the underworld.
The identification of the god behind Caesar's description has been a long-standing subject of Celtic religious research. The most often cited candidate for "Gaulish Dis Pater" is Sucellus, a mallet-wielding god of the Gauls. The arguments for this identification are largely based on iconographic parallels with mallet-wielding figures in Etruscan, Greek, and Roman mythology. Other major candidates include Taranis, the only Celtic god elsewhere identified with Dis Pater in classical literature, and Cernunnos, a Celtic god who perhaps had chthonic/fertility associations.
The passage in which Caesar described Gaulish Dis Pater has also been appreciated for the light it throws on Celtic date-keeping, and its innovative ethnographic methods. Greco-Roman ethnography prior to Caesar usually attempted to fit the origins of barbarian peoples into Greek mythological frameworks. Caesar broke with this in reproducing a native Gaulish tradition about their descent. Elias Bickerman deemed this passage a "Copernican discovery" in the history of Greco-Roman ethnography.
Caesar and Gaulish Dis Pater
The Commentaries on the Gallic War is Caesar's first-hand account of the Gallic Wars, written during or shortly after those wars. His first-hand acquaintance with the Gauls makes the work an invaluable source for Gaulish religion, although not an unproblematic one. In Book 6 of the Commentaries, Caesar describes the five main deities worshipped in Gaul ; in the following section he adds one more to this pantheon:Caesar refers to the Gaulish god from whom the Celts claimed descendance under the name of a Roman god, Dis Pater. Such a practice, of referring to foreign deities under Roman names, was called by Tacitus the interpretatio romana. A foreign god was equated with a Roman one on the basis of their similarity, however superficial; usually it was sufficient that the gods have one sphere of influence in common. The practice was fairly flexible in the Celtic regions, where one Celtic god could have multiple Roman equivalents, and one Roman god many Celtic equivalents. In Roman accounts of Celtic or Germanic religion, the application of interpretatio romana is the rule. Nonetheless, Caesar's application of this device in one of the most detailed surviving accounts of Celtic religion has caused much difficulty for scholars. The identification of Gaulish Dis Pater has been a long-standing subject of Celtic religious research.
An excursus on the origin of Celtic people is a frequent feature of classical ethnographies of the Celts. However, classical ethnographies of barbarian peoples prior to Caesar, as a rule, gave Greek mythological explanations of their origins. Thus, Timaeus explains the Galatians as descendants of Galates, a son of Polyphemus; and Parthenius explains the Celts as descendants of Keltus, a son of Heracles; among many other such traditions. Caesar broke with this tradition in reproducing, and crediting, a native Celtic tradition about their own origins. Elias Bickerman refers to this a "Copernican discovery" in the history of Greco-Roman ethnography.
Caesar connects the druidic traditions about Gaulish Dis Pater with the Celtic practice of date-keeping by nights. Evidence for this practice among the Celts is otherwise given by the Gaulish words designating three- and ten-day feasts, tri-noxtion and decam-noctiacus, and the modern Welsh words for week and fortnight, wythnos and pythefnos. Though unfamiliar to the Romans, such a method of date-keeping is not cross-culturally rare; the Greeks, Arabs, and Germanic peoples all made some use of it. It is not clear whether the connection between date-keeping and Gaulish Dis Pater is a surmise of Caesar's or a tradition of the druids.
Dis Pater in Rome and in the Celtic provinces
Dis Pater was the Roman god of the underworld and of prosperity. Dis Pater seems to have been invented for the Tarentine Games as a Roman equivalent of the Greek god Pluto. As even the Romans acknowledged, the name Dis is a direct translation of the Greek name Pluto. Outside of the Tarentine Games, Dis Pater played only a minor part in Roman religion. Only two identifiable images of him have survived. Dis Pater appears most prominently in Latin literature, where he takes the place that Pluto/Hades occupies in Greek literature.The archaeological evidence for the worship of Dis Pater in the Celtic provinces is very limited. If Gaulish Dis Pater was as important as Caesar made out, the interpretatio Caesar offers cannot have been much adopted. In any case, this evidence is of little help in identifying Gaulish Dis Pater. An inscription from Bregenz perhaps identifies the Celtic god Smertrios with Dis Pater. However, the reading is not very certain, and Smertrios is more usually identified with Mars. One heterodox aspect of Dis Pater's cult in the Western provinces is that he is frequently paired with the goddess Erecura. However, little is understood about her cult so this does not aid much in the identification of Gaulish Dis Pater.
Candidates
Sucellus
Sucellus is a Celtic god is best known from his distinctive and well-attested iconography, in which he is depicted with a mallet and an olla. His nature as a god is not clear. The Roman god most closely associated with Sucellus was Silvanus, Roman god of the countryside. In Gallo-Roman iconography, Silvanus occasionally borrows the mallet and olla of Sucellus. In turn, Sucellus's iconography borrows from classical models, particularly those of the Roman god Jupiter and the Greek gods Pluto and Charon.Sucellus is the god most often equated with Gaulish Dis Pater in modern scholarship. The argument for this identity is based on iconographic parallels. Sucellus's mallet plays a central role in such arguments. The characteristic mallet of the Etruscan psychopomp Charun has frequently been cited. The Greek god Dionysius, who had a chthonic aspect, was occasionally depicted with a similar mallet. To show that Dis Pater was similarly associated with the mallet, a passage from Tertullian has frequently been adduced. Tertullian records that, during Roman games, a slave dressed as Dis Pater used a mallet to drag corpses from the arena. Stéphanie Boucher is sceptical of the value of this comparison, arguing that this custom does not prove an association of Dis Pater with the mallet as much as it does an association of Dis Pater with Charun.
Some later myths and customs in Celtic nations have been cited to substantiate the proposed chthonic associations of the mallet among the Celts. Other iconographic features of Sucellus have been incorporated into this interpretation. Some monuments of a mallet-wielding god iconographically echo depictions of Hades/Pluto. The tunic of Charon bears a resemblance to the Gallic clothing of Sucellus.
Against this hypothesis, de Vries has pointed to the limited distribution of Sucellus and the fact that the interpretatio romana of Sucellus as Jupiter is favoured by the epigraphic evidence. Boucher argues that the former point has no worth, as all representations of gods are rare in the west of Gaul.
Taranis
Taranis was a Celtic thunder god, and is one of the few Celtic gods known by his native name in classical literature, referenced as such in the Roman poet Lucan's epic Pharsalia. Lucan's poem was a popular school text, which created a demand for commentaries and scholia dealing with difficulties in grammar and subject matter. The best known collection of such scholia is the Commenta Bernensia, a set of notes to the poem preserved in an 11th-century CE manuscript, and with textual layers which date from the 4th to the 9th century CE. In glossing the passage in which Taranis is mentioned, the Commenta Bernensia notes that the sources available to it give different interpretatios of Taranis: some identify Taranis with Jupiter, and others identify Taranis with Dis Pater.The Commenta Bernensia is the only other classical text to mention Dis Pater in relation to Celtic religion. It is difficult to evaluate the origin and significance of the Commenta equation of Taranis with Dis Pater. The equation with Jupiter is better represented in the commentary tradition to Lucan and confirmed by inscriptions; the parallel between Taranis and Jupiter's role as thunder gods is clear. On the other hand, Manfred Hainzmann points out Dis was associated in Latin literature with the night sky and night thunderstorms. Statius, for example, refers to Dis Pater as the "thunderer of the underworld". Taranis is sometimes identified with the Celtic wheel god. Fritz Heichelheim and Pierre Lambrechts have attempted to substantiate the connection between Taranis and Gaulish Dis Pater through features of this wheel god.
Cernunnos
Cernunnos is a Celtic god also primarily known from his distinctive iconography, in which he is portrayed as a cross-legged, deer-antlered man adorned with torcs. The surviving evidence does not attest to any interpretatio romana for this distinctly Celtic god, but it does repeatedly associate him with the Roman god Mercury. His attributes identify Cernunnos as a god of fertility and abundance. A chthonic association for this fertility god has also been repeatedly proposed.Phyllis Pray Bober and Robert Mowat have argued that Cernunnos is a natural candidate for an interpretatio of Dis Pater, as a god with a similar chthonic-fertility character. Bober also compared Cernunnos's association with bags of coins and Dis Pater's with underground metals.