No name in connection with Celtic religion is more familiar to the average reader than that of the Druids, yet there is no section of the history of Celtic religion that has given rise to greater discussion than that relating to this order. Even the association of the name with the Indo-European root dru-, which we find in the Greek word drus, an oak, has been questioned by such a competent Celtic scholar as M. d’Arbois de Jubainville, but on this point it cannot be said that his criticism is conclusive. The writers of the ancient world who refer to the Druids, do not always make it sufficiently clear in what districts the rites, ceremonies, and functions which they were describing prevailed. Nor was it so much the priestly character of the Druids that produced the deepest impression on the ancients. To some philosophical and theological writers of antiquity their doctrines and their apparent affinities with Pythagoreanism were of much greater interest than their ceremonial or other functions. One thing at any rate is clear, that the Druids and their doctrines, or supposed doctrines, had made a deep impression on the writers of the ancient world. There is a reference to them in a fragment of Aristotle (which may not, however, be genuine) that is of interest as assigning them a place in express terms both among the Celts and the GalatÆ. The prominent feature of their teaching which had attracted the attention of other writers, such as the historian Diodorus Siculus and the Christian theologian Clement of Alexandria, was the resemblance of their doctrine concerning the immortality and transmigration of the soul to the views of Pythagoras. Ancient writers, however, did not always remember that a religious or philosophical doctrine must not be treated as a thing apart, but must be interpreted in its whole context in relation to its development in history and in the social life of the community in which it has flourished. To some of the ancients the superficial resemblance between the Druidic doctrine of the soul’s future and the teaching attributed to Pythagoras was the essential point, and this was enough to give the Druids a reputation for philosophy, so that a writer like Clement of Alexandria goes so far as to regard the Druids of the ‘GalatÆ’ along with the prophets of the Egyptians, the ‘ChaldÆans’ of the Assyrians, the ‘philosophers of the Celts,’ and the Magi of the Persians as the pioneers of philosophy among the barbarians before it spread to the Greeks. The reason for the distinction drawn in this passage between the ‘Druids of the GalatÆ’ and ‘the philosophers of the Celts’ is not clear. Diodorus Siculus calls attention to the Druidic doctrine that the souls of men were immortal, and that after the lapse of an appointed number of years they came to life again, the soul then entering into another body. He says that there were certain ‘philosophers and theologians’ that were called Druids who were held in exceptional honour. In addition to these, the Celts, he says, had also seers, who foretold the future from the flight of birds and by means of the offering of sacrifices. According to him it was these priestly seers who had the masses in subjection to them. In great affairs they had, he says, the practice of divination by the slaughter of a human victim, and the observation of the attitude in which he fell, the contortions of the limbs, the spurting of the blood, and the like. This, he states, was an ancient and established practice. Moreover, it was the custom, according to Diodorus, to make no sacrifice without the presence of a philosopher (apparently a Druid in addition to the sacrificing seer), the theory being that those who were authorities on the divine nature were to the gods intelligible mediators for the offering of gifts and the presentation of petitions. These philosophers were in great request, together with their poets, in war as well as in peace, and were consulted not merely by the men of their own side, but also by those of the enemy. Even when two armies were on the point of joining battle, these philosophers had been able, Diodorus says, to step into the space between them and to stop them from fighting, exactly as if they had charmed wild beasts. The moral which Diodorus draws from this is, that even among the wildest of barbarians the spirited principle of the soul yields to wisdom, and that Ares (the god of war) even there respects the Muses. It is clear from this account that Diodorus had in mind the three classes of non-military professional men among the Celts, to whom other ancient writers also refer, namely, the Bards, the Seers, and the Druids. His narrative is apparently an expansion, in the light of his reading and philosophical meditation, of information supplied by previous writers, notably Posidonius. The latter, too, appears to have been Julius CÆsar’s chief authority, in addition to his own observation, but CÆsar does not appear expressly to indicate the triple division here in question. The account which he gives is important, and would be even more valuable than it is had he told us how far what he describes was written from his own personal information, and the degree of variation (if any) of religious practice in different districts. However, CÆsar’s statements deserve the closest consideration. After calling attention to the division of the Gaulish aristocracy into two main sections, the Druids and the Knights, he proceeds to speak of the Druids. These were occupied, he says, with religious matters, they attended to public and private sacrifices, and interpreted omens. Moreover, they were the teachers of the country. To them the young men congregated for knowledge, and the pupils held their teachers in great respect. They, too, were the judges in public and private disputes: it was they who awarded damages and penalties. Any contumacy in reference to their judgments was punished by exclusion from the sacrifices. This sentence of excommunication was the severest punishment among the Gauls. The men so punished were treated as outlaws, and cut off from all human society, with its rights and privileges. Over these Druids there was one head, who wielded the highest influence among them. On his death the nearest of the others in dignity succeeded him, or, if several were equal, the election of a successor was made by the vote of the Druids. Sometimes the primacy was not decided without the arbitrament of arms. The Druids met at a fixed time of the year in a consecrated spot in the territory of the Carnutes, the district which was regarded as being in the centre of the whole of Gaul. This assembly of Druids formed a court for the decision of cases brought to them from everywhere around. It was thought, CÆsar says, that the doctrine of the Druids was discovered in Britain and thence carried over into Gaul. At that time, too, those who wanted to make a profounder study of it resorted thither for their training. The Druids had immunity from military service and from the payment of tribute. These privileges drew many into training for the profession, some of their own accord, others at the instance of parents and relatives. While in training they were said to learn by heart a large number of verses, and some went so far as to spend twenty years in their course of preparation. The Druids held it wrong to put their religious teaching in writing, though, in almost everything else, whether public or private affairs, they made use of Greek letters. CÆsar thought that they discouraged writing on the one hand, lest their teaching should become public property; on the other, lest reliance upon writing should lessen the cultivation of the memory. To this risk CÆsar could testify from his own knowledge. Their cardinal doctrine was that souls did not perish, but that after death they passed from one person to another; and this they regarded as a supreme incentive to valour, since, with the prospect of immortality, the fear of death counted for nothing. They carried on, moreover, many discussions about the stars and their motion, the greatness of the universe and the lands, the nature of things, the strength and power of the immortal gods, and communicated their knowledge to their pupils. In another passage CÆsar says that the Gauls as a people were extremely devoted to religious ideas and practices. Men who were seriously ill, who were engaged in war, or who stood in any peril, offered, or promised to offer, human sacrifices, and made use of the Druids as their agents for such sacrifices. Their theory was, that the immortal gods could not be appeased unless a human life were given for a human life. In addition to these private sacrifices, they had also similar human sacrifices of a public character. CÆsar further contrasts the Germans with the Gauls, saying that the former had no Druids to preside over matters of religion, and that they paid no attention to sacrifices.

In his work on divination, Cicero, too, refers to the profession which the Druids made of natural science, and of the power of foretelling the future, and instances the case of the Æduan Divĭciācus, his brother’s guest and friend. Nothing is here said by Cicero of the three classes implied in Diodorus, but Timagenes (quoted in Ammianus) refers to the three classes under the names ‘bardi,’ ‘euhages’ (a mistake for ‘vates’), and ‘drasidÆ’ (a mistake for ‘druidÆ’). The study of nature and of the heavens is here attributed to the second class of seers (vates). The highest class, that of the Druids, were, he says, in accordance with the rule of Pythagoras, closely linked together in confraternities, and by acquiring a certain loftiness of mind from their investigations into things that were hidden and exalted, they despised human affairs and declared the soul immortal. We see here the view expressed that socially as well as intellectually the Druids lived according to the Pythagorean philosophy. Origen also refers to the view that was prevalent in his time, that Zamolxis, the servant of Pythagoras, had taught the Druids the philosophy of Pythagoras. He further states that the Druids practised sorcery. The triple division of the non-military aristocracy is perhaps best given by Strabo, the Greek geographer, who here follows Posidonius. The three classes are the Bards, the Seers (ouateis=vates), and Druids. The Bards were hymn-writers and poets, the Seers sacrificers and men of science, while the Druids, in addition to natural science, practised also moral philosophy. They were regarded as the justest of men, and on this account were intrusted with the settlement of private and public disputes. They had been the means of preventing armies from fighting when on the very verge of battle, and were especially intrusted with the judgment of cases involving human life. According to Strabo, they and their fellow-countrymen held that souls and the universe were immortal, but that fire and water would sometime prevail. Sacrifices were never made, Strabo says, without the intervention of the Druids. Pomponius Mela says that in his time (c. 44 a.d.), though the ancient savagery was no more, and the Gauls abstained from human sacrifices, some traces of their former practices still remained, notably in their habit of cutting a portion of the flesh of those condemned to death after bringing them to the altars. The Gauls, he says, in spite of their traces of barbarism, had an eloquence of their own, and had the Druids as their teachers in philosophy. These professed to know the size and form of the earth and of the universe, the motions of the sky and stars, and the will of the gods. He refers, as CÆsar does, to their work in education, and says that it was carried on in caves or in secluded groves. Mela speaks of their doctrine of immortality, but says nothing as to the entry of souls into other bodies. As a proof of this belief he speaks of the practice of burning and burying with the dead things appropriate to the needs of the living. Lucan, the Latin poet, in his Pharsalia, refers to the seclusion of the Druids’ groves and to their doctrine of immortality. The Scholiasts’ notes on this passage are after the manner of their kind, and add very little to our knowledge. In Pliny’s Natural History (xvi, 249), however, we seem to be face to face with another, though perhaps a distorted, tradition. Pliny was an indefatigable compiler, and appears partly by reading, partly by personal observation, to have noticed phases of Celtic religious practices which other writers had overlooked. In the first place he calls attention to the veneration in which the Gauls held the mistletoe and the tree on which it grew, provided that that tree was the oak. Hence their predilection for oak groves and their requirement of oak leaves for all religious rites. Pliny here remarks on the consonance of this practice with the etymology of the name Druid as interpreted even through Greek (the Greek for an oak being drūs). Were not this respect for the oak and for the mistletoe paralleled by numerous examples of tree and plant-worship given by Dr. Frazer and others, it might well have been suspected that Pliny was here quoting some writer who had tried to argue from the etymology of the name Druid. Another suspicious circumstance in Pliny’s account is his reference to the serpent’s egg composed of snakes rolled together into a ball. He states that he himself had seen such an ‘egg,’ of about the size of an apple. Pliny, too, states that Tiberius CÆsar abolished by a decree of the Senate the Druids and the kind of seers and physicians the Gauls then had. This statement, when read in its context, probably refers to the prohibition of human sacrifices. The historian Suetonius, in his account of the Emperor Claudius, also states that Augustus had prohibited ‘the religion of the Druids’ (which, he says, ‘was one of fearful savagery’) to Roman citizens, but that Claudius had entirely abolished it. What is here also meant, in view of the description given of Druidism, is doubtless the abolishing of its human sacrifices. In later Latin writers there are several references to Druidesses, but these were probably only sorceresses. In Irish the name drÚi (genitive druad) meant a magician, and the word derwydd in mediÆval Welsh was especially used in reference to the vaticinations which were then popular in Wales.

When we analyse the testimony of ancient writers concerning the Druids, we see in the first place that to different minds the name connoted different things. To CÆsar it is the general name for the non-military professional class, whether priests, seers, teachers, lawyers, or judges. To others the Druids are pre-eminently the philosophers and teachers of the Gauls, and are distinguished from the seers designated vates. To others again, such as Pliny, they were the priests of the oak-ritual, whence their name was derived. In view of the variety of grades of civilisation then co-existing in Gaul and Britain, it is not improbable that the development of the non-military professional class varied very considerably in different districts, and that all the aspects of Druidism which the ancient writers specify found their appropriate places in the social system of the Celts. In Gaul and Britain, as elsewhere, the office of the primitive tribal medicine-man was capable of indefinite development, and all the forms of its evolution could not have proceeded pari passu where the sociological conditions found such scope for variation. It may well be that the oak and mistletoe ceremonies, for example, lingered in remote agricultural districts long after they had ceased to interest men along the main routes of Celtic civilisation. The bucolic mind does not readily abandon the practices of millennia.

In addition to the term Druid, we find in Aulus Hirtius’ continuation of CÆsar’s Gallic War (Bk. viii., c. xxxviii., 2), as well as on two inscriptions, one at Le-Puy-en-Velay (Dep. Haute-Loire), and the other at MÂcon (Dep. SaÔne-et-Loire), another priestly title, ‘gutuater.’ At MÂcon the office is that of a ‘gutuater Martis,’ but of its special features nothing is known.