Esus

Esus is a Celtic god known from iconographic, epigraphic, and literary sources.
The 1st-century CE Roman poet Lucan's epic Pharsalia mentions Esus, Taranis, and Teutates as gods to whom the Gauls sacrificed humans. This rare mention of Celtic gods under their native names in a Greco-Roman text has been the subject of much comment. Almost as often commented on are the scholia to Lucan's poem which tell us the nature of these sacrifices: in particular, that Esus's victims were suspended from a tree and bloodily dismembered. The nature of this ritual is obscure, but it has been compared with a wide range of sources, including Welsh and Germanic mythology, as well as with the violent end of the Lindow Man.
Esus has been connected with a pictorial myth on the Pillar of the Boatmen, a Gallo-Roman column from Paris. This myth associates Esus, felling or pruning a tree, with a bull and three cranes. A similar monument to Esus and Tarvos Trigaranos from Trier confirms this association. The nature of this myth is little understood; it at least confirms the scholia's association of Esus with trees.
Esus appears rarely in inscriptions, with only two certain attestations of his name in the epigraphic record. His name appears more commonly as an element of personal names. While Lucan only attributes the worship of Esus to unspecified Gauls, inscriptions place the worship of Esus in Gaul, Noricum, and perhaps Roman North Africa; personal names may also place his worship in Britain. In inscriptions, Esus is attested as early as the 1st century BCE. In Latin literature, he may appear as late as the 5th century CE.

Etymology

A large number of etymologies have been proposed for the name "Esus". The nature of the god's name is not certain. has suggested it may be a euphemism, cover-name, or epithet of the god. has even questioned whether "Esus" was a name given to only one deity.
The most widely adopted etymology derives Esus's name from the proto-Indo-European verbal root h₁eis-, cognate with Italic aisos. This etymology is supported by the fact that it makes the initial vowel of Esus's name long, which agrees with both Lucan's poetic stress and the variant spellings which use "ae" for this vowel. However, D. Ellis Evans points out that the more common etymology for Italic aisos derives this word from an Etruscan word; since Etruscan is non-Indo-European and Celtic is Indo-European, this would rule out a relationship between Esus and aisos.
Joseph Vendryes linked the name with proto-Indo-European *. Jan de Vries is sceptical of this, pointing out that this is difficult to reconcile with the fearful god described in Lucan and the scholia. Meid suggests the name would then be a euphemism, comparing it with the Irish god-name Dagda. Henri d'Arbois de Jubainville linked it to proto-Indo-European *. T. F. O'Rahilly linked it to proto-Indo-European *. Félix Guirand suggested the name was cognate with Latin erus, which Meid notes is a common epiclesis given to deities. Other etymologies have variously connected the name with German Ehre, Ancient Greek αἰδέομαι, Old Norse eir, and Breton heuzuz

Lucan and the scholia

Lucan

Lucan's Pharsalia or De Bello Civili is an epic poem, begun about 61 CE, on the events of Caesar's civil war. The passage relevant to Esus occurs in "Gallic excursus", an epic catalogue detailing the rejoicing of the various Gaulish peoples after Julius Caesar removed his legions from Gaul to Italy. The passage thus brings out two themes of Lucan's work, the barbarity of the Gauls and the unpatriotism of Caesar.
The substance of the last few lines is this: unspecified Gauls, who made human sacrifices to their gods Teutates, Esus, and Taranis, were overjoyed by the exit of Caesar's troops from their territory. The reference to "Diana of the Scythians" refers to the human sacrifices demanded by Diana at her temple in Scythian Taurica, well known in antiquity. That Lucan says little about these gods is not surprising. Lucan's aims were poetic, and not historical or ethnographic. The poet never travelled to Gaul and relied on secondary sources for his knowledge of Gaulish religion. When he neglects to add more, this may well reflect the limits of his knowledge.
We have no literary sources prior to Lucan which mention these deities, and the few which mention them after Lucan seem to borrow directly from this passage. The secondary sources on Celtic religion which Lucan relied on in this passage have not come down to us, so it is hard to date or contextualise his information. This passage is one of the very few in classical literature in which Celtic gods are mentioned under their native names, rather than identified with Greek or Roman gods. This departure from classical practice likely had poetic intent: emphasising the barbarity and exoticness the Gauls, whom Caesar had left to their own devices.
Some scholars, such as de Vries, have argued that the three gods mentioned together here formed a divine triad in ancient Gaulish religion. However, there is little other evidence associating these gods with each other. Other scholars, such as Graham Webster, emphasise that Lucan may as well have chosen these deity-names for their poetic stress and harsh sound.

Scholia

Lucan's Pharsalia was a very popular school text in late antiquity and the medieval period. This created a demand for commentaries and scholia dealing with difficulties in the work, both in grammar and subject matter. The earliest Lucan scholia that have come down to us are the Commenta Bernensia and Adnotationes Super Lucanum, both from manuscripts datable between the 9th and 11th centuries. In spite of their late date, the Commenta and Adnotationes are thought to incorporate very ancient material, some of it now lost; both are known to contain material at least as old as Servius the Grammarian. Also interesting, though less credible, are comments from a Cologne codex, dating to the 11th and 12th centuries. Below are excerpts from these scholia relevant to Esus:

Commentary	Latin	English
Commenta Bernensia ad Lucan, 1.445	Hesus Mars sic placatur: homo in arbore suspenditur usque donec per cruorem membra digesserit.	Hesus Mars is appeased in this way: a man is suspended from a tree until his limbs are divided as a result of the bloodshed.
Commenta Bernensia ad Lucan, 1.445	item aliter exinde in aliis invenimus. Hesum Mercurium credunt, si quidem a mercatoribus colitur	We also find it differently by other . They believe Hesus to be Mercury, because he is worshipped by the merchants
Adnotationes super Lucanum, 1.445.	Esus Mars sic dictus a Gallis, qui hominum cruore placatur.	Esus is the name given by the Gauls to Mars, who is appeased with human blood.
Glossen ad Lucan, 1.445	Esus id est Mars.	Esus, that is Mars.

The first excerpt, about the sacrifice to Esus, comes from a passage in the Commenta which details the human sacrifices offered to each of the three gods. This passage, which is not paralleled anywhere else in classical literature, has been the subject of much commentary. It seems to have been preserved in the Commenta by virtue of its author's preference for factual explanation. The Adnotationes, by comparison, tell us nothing about the sacrifices to Esus, Teutates, and Taranis beyond that they were each murderous. The nature of the sacrifice to Esus described here is unclear; the Latin text is cramped and ambiguous. Early Celticists relied on drastic emendations to the text, which have not been sustained in later scholarship. To give a few difficulties: digesserit here could refer to a process of decomposition or a violent severing of the limbs; cruor means "blood" and "raw meat", but also metaphorically "murder"; and in arbore suspenditur, often read as suggesting that Esus's victims were hanged by the neck from a tree, is perhaps nearer in meaning to saying that his victims were "fixed to" or "suspended from a tree".
As a result of this ambiguity, a very large number of interpretations of the sacrificial ritual to Esus have been given. It has been pointed out that hanging by the neck does not result in loss of blood; and that neither of these lead to a dislocation of the limbs. Suggestions include that the victim was tied to the tree in order to be dismembered; or dismembered by means of tree branches; or injured and then suspended from the tree, by their armpits or limbs. This ritual has been compared with various legendary demises: the human sacrifices to Odin, the death of the mythological Welsh hero Lleu Llaw Gyffes, and the martyrdom of St Marcel de Chalon. The violent end of the bog body known as the Lindow Man—throat slashed, strangled, bludgeoned, and drowned—has even been connected with this sacrificial ritual.
All three commentaries offer an interpretatio romana which identifies Esus as Mars. The scholiast of the Commenta, however, notes that other sources give an interpretatio of Esus as Mercury, for which they offer a rationale: Esus, like Mercury, was worshipped by merchants. It is not possible to demonstrate the authenticity of either of these equations, as we have no source outside these commentaries which pairs the name of Esus with that of a Roman god. The evident confusion of the sources the scholiast had available to him has been taken to count against the evidentiary value of either of these interpretatios. regards the equation of Esus with Mercury as unlikely, because the Trier monument depicts Esus and Mercury next to each other, as separate divinities. On the other hand, a Mercury statue from Lezoux is sometimes believed to have a dedicatory inscription to Esus on its rear, which may count in favour of the existence of such an interpretatio.