Julius Caesar’s memoir Commentarii De Bello Gallico (‘Commentary On the Gallic War’) was an account of the Roman army’s subjugation of Gaul in 51BCE and which he himself led.

The work is famous for its descriptions of the enigmatic priestly caste of the Gauls: the Druids. These were leaders of the ancient religious system then common to Gaul, Britannia and Hibernia/Scotia (Ireland). He says very little about the religion itself, being more interested in expressing the Druids’ political and social importance, but he does give a few tantalising details… (Translations by W. A. McDevitte and W. S. Bohn)

They wish to inculcate this as one of their leading tenets, that souls do not become extinct, but pass after death from one body to another, and they think that men by this tenet are in a great degree excited to valour, the fear of death being disregarded.

… and about their gods he has this to say:

All the Gauls assert that they are descended from the god Dis, and say that this tradition has been handed down by the Druids.

As well as naming ‘Dis’, Caesar used the convention of giving Roman names for the rest of the gods of the Gauls and describes ‘Mercury’ as their chief deity, as well as Apollo, Mars, Jupiter, and Minerva. As war is perhaps the least satisfactory arena in which to study cultural anthropology, his is probably a very rough and unreliable overview of the reality of Gaulish religion. After all, this was an era where even the Romans were confused about their own gods and religion: To contemporary intellectuals (such as followers of the 4thC BCE Hellenic philosopher Plato) gods were scientific expressions of universal phenomena, not to be taken literally. To the masses, they were a literal truth – an unseen power made visible and understood through images and ceremonies. Religion was diversifying at an alarming and unsustainable rate. His appraisal of the Gauls and the contradistinction he makes with the German tribes in chapter 21 (where he claims that they had no druids and worshipped only what they saw – the sun, fire and the moon) have underpinned the study of European paganism ever since, but it is likely that the Gauls, Britons, Irish and Germans probably shared very similar beliefs, which the mediterranean mind found it difficult to conceptualise.

The thing is… there is very little evidence of the exact nature of Pre-Roman/Pre-Hellenic religion among Iron Age ‘Celtic’ or German tribes. What exists is – like Caesar’s account – seen from a very jaded Roman or Greek viewpoint. There is ample evidence of Romanised ‘Celtic’ deities from the next 5 centuries after Caesar, and even before he took Gaul its southern part was under the cultural influence of the Hellenes (and was probably itself influential upon the Greek world). Familiar attested names of ‘gods’ such as ‘Toutatis’, ‘Taranis’, ‘Belenos’, ‘Cernunnos’ and so forth remain as popular totems that have scant evidence linking them to a systematic beliefs, and perhaps the biggest problem is that folklore from the more modern celtic world that preserves obvious and fundamental pre-chistian beliefs does not offer much support for a Roman-style pantheon of gods. The reasons for this need to be and will be investigated in my writing.

The most important key belief that Caesar mentions is that the soul flies free of the body after death and returns to another corporeal existence in time. Such a belief is the core of an ancestor-based religion. Also the Gaulish god Caesar calls ‘Dis’ (to the Romans a psychopomp or conductor of souls, and guardian of the earth’s fertility and mystery) was believed to be the racial forefather, thus making him/it the key archetype god for this soul-belief. When he omits mentioning ‘Dis’ in his assessment of Gaul’s most important totem gods in the previous chapter, he is probably seeking to discourse on something the Romans knew more about. Roman ‘Mercury’ (Hermes to the Greeks) was also a psychopomp (conductor of souls) and Caesar may well have been using the names ‘Mercury’ and ‘Dis’ (as well as ‘Mars’, ‘Apollo’ and ‘Jupiter’) to refer to the same important progenitor divinity, and I will present evidence for this in due course. His intention with the interpretatio romanum was also possibly an attempt to orientate his Roman readers to similarities between them and the Gauls, especially as many would own Gaulish slaves as a result of his campaign. The core domestic (and plebian) religion of Rome was, after all, based upon ancestor-spirit worship (of ‘Lares’ and ‘Genii’ as well as ‘Lemures’, ‘Larvae’ and ‘Manes’) and veneration of the ‘eternal gods’ (Jupiter etc) was generally seen as a more high-minded and public affair, albeit open to fads and trends, and imperial decree. The Roman beliefs in disincarnate souls therefore showed a distinct commonality with their ‘Celtic’ neighbours, and is in evidence among Rome’s Etruscan forerunners.

In christian times, it seems that stubbornly tenuous pagan ideas about discarnate ‘souls’ were to become identified with ‘fairies’ – spirits who inhabited an inverted parallel world to our own, their daytime being our night, and vice versa… Fairy belief was to become a cultural shibboleth of Atlantic Celtic peoples.