Strabo, being a meticulous and conscientious scholar, naturally relied entirely on his sources when it came to regions such as Gaul and Britain that he had no personal experience with. The majority of these were Greek, and the few Roman authors he was acquainted with were, at best, in shoddy condition. His geographical account of Gaul is rife with errors; for instance, he incorrectly positions the Aquitani people in the region’s center when they actually inhabited the southwestern part.

This appears to be the result of his reliance on a defective edition of Caesar’s book on the Gallic war. His depiction of indigenous practices is linked to the clans that once inhabited the northern region of Gaul, extending beyond the Rhône and Garonne valleys.

Strabo made it clear that he was not referring to the lifestyle of the affected peoples during his own era, when they were long under Roman rule, but rather to “as we understand them to have existed in the past.” It is noteworthy that while he frequently cited the sources he utilized, he neglected to do so with regard to his passages pertaining to Druids or the women residing on the island. They seem to be rumors, possibly acquired during his sojourn in Italy.

When discussing the methods employed by the Gauls to perform human sacrifices, he tactfully disassociated himself from the details by employing the conjunction “it is said.” In order to provide his account of the women, he retreated an additional distance. The author began and concluded the passage with the phrase “they say,” which suggested that the information was unrelated to any of the esteemed academicians whose works are extensively cited in the text. Moving on to relate another story about indigenous divination techniques, he vehemently implied that he did not personally believe it, remarking that it was “even more obviously fictitious” than the one concerning the island. Archaeology can occasionally refute one of Strabo’s claims. Undoubtedly, the Gauls relished in golden bracelets and collars—the renowned “torques” of twisted metal—as evidenced by their unearthing during excavations.

Conversely, Gallic attire continued to be prevalent during his lifetime and may have even been observed in Rome; in contrast, the indigenous religious practices, as previously mentioned, had undergone modifications and no such discernible evidence remains in the material record. In addition, archaeology occasionally disproves his claims, such as the claim that the British lacked permanent settlements during his era. Strabo, similar to Caesar, had a clear intention of magnifying the destitution of British culture. He supported his account with the argument that it validated the Romans’ earlier failure to conquer the island; the location was not worth the expense of occupancy.

The third and final author was Pomponius Mela, an individual of Spanish descent who appeared to have maintained a residence in Rome. He is renowned for his concise overview of the global geography. He noted in this passage that Roman law had rendered human sacrifice a clandestine practice among the Gauls by the time of him (around 40 CE). He further stated that the Druidas, who claimed to know “the size and shape of the world, the movements of the heavens, and the will of the deities,” could still be held in high regard as teachers of wisdom. They convened in covert locations such as caverns or secluded valleys, where they imparted knowledge to youthful Gallic nobles over the course of twenty years.

‘That souls are eternal and that there is another existence in the world below’ was the only widely known of their teachings. However, this doctrine spread rapidly because it inspired the Gauls to be more courageous in battle. In addition, they burned or buried with the deceased any items that were necessary for survival, and in the past, they postponed the settlement of obligations and the conclusion of business transactions until they reached the afterlife. Certain individuals willingly disposed of themselves atop funeral pyres so as to promptly transition into a new existence alongside the deceased. Pomponius supplemented the account cited by Strabo with an anecdote concerning an island populated by priestesses. His island, situated between Britain and Gaul, was inhabited by nine women who served an oracle and had sworn to perpetual virginity. They were referred to as Senae by the Gauls, who believed that their melodies could conjure storms, transform them into animals, cure any ailment, and foretell the future.

Much time has been devoted by contemporary scholars to analyzing the sources utilized by all three authors. Once upon a time, it was hypothesized that Strabo was supplementing a medley of Caesar and Diodorus with a few additional details, and that Pomponius was merely a revival of Caesar with some imaginative flourishes.

While the final argument may still be valid, it is also possible that Pomponius was relying on a source or sources that have since been lost entirely. Regarding Diodorus and Strabo, an attempt has been made to simplify the situation. Since the 1950s, there has been an overwhelmingly accepted belief that the depiction of Gaul in both accounts is derived from a solitary misplaced source: the writings of Posidonius, a Greek philosopher hailing from Syria, who traveled to the eastern region of Gaul during the early first century BCE. Furthermore, there has been speculation that Posidonius could have been the preceding authority that Caesar referenced in his preconceived notion of Gallic society. Should this be the case, then the authority pertaining to the Druids prior to the Roman conquest is essentially derived from the indirect testimonies of a single traveler.

Scholars of the era have thus coined the term “Posidonian tradition” to refer to Greek and Roman writings concerning the ancient Druids. This tradition is distinguished by two seemingly contradictory characteristics found in the aforementioned accounts: first, that the Druids were highly developed scientists and philosophers who firmly believed in the immortality of the soul; and second, that they engaged in mass human sacrifices through various heinous methods. Consequently, they elicited both admiration and contempt. Two components of this image have been contested by various contemporary scholars.

Stuart Piggott, Daphne Nash, and David Rankin posit that Posidonius romanticized tribal peoples as embodiments of primal innocence and natural wisdom, and that he exaggerated the sophistication of Druidic teaching by imposing Greek philosophical concepts upon it. While some authors speculate that he may have applied a rose hue to the Druids, others propose that he darkened them. His veneration of Rome has been brought to light by Jane Webster and Peter Berresford Ellis, who have accused him of serving as its propagandist through the barbaric treatment of the Gallic tribes.

Piggott observed that the account of human sacrifice involving the lethal discharge of missiles is peculiar, given that archery is conspicuously absent from historical accounts of the Gauls or comparable civilizations. Webster further advises that due to the fact that Posidonius solely explored a single region of Gaul, his accounts might have been applicable solely to that area. As a result, every facet of the Posidonian tradition, which appears to be our most dependable source for the whereabouts of the ancient Druids, has been contested.