Caesar provides us with much information regarding the Druids as well as a wealth of knowledge about iron-age customs and traditions, and the social structures within iron-age society. Much of Caesar's narrative concerns the people of Gaul, who were culturally identical to the inhabitants of Britain, so nearly all that he wrote of Gallic druidism may be equally applied to druidism in Britannia.
"13 Throughout gaul there are two classes of persons of definite account and dignity. As for the common folk, they are treated almost as slaves, venturing naught of themselves, never taken into counsel. The more part of them, oppressed as they are either by debt, or by the heavy weight of tribute, or by the wrongdoing of the more powerful men, commit themselves in slavery to the nobles, who have, in fact, the same rights over them as masters over slaves. Of the two classes above mentioned one consists of Druids, the other of knights. The former are concerned with divine worship, the due performance of sacrifices, public and private, and the interpretation of ritual questions: a great number of young men gather about them for the sake of instruction and hold them in great honour. In fact, it is they who decide in almost all disputes, public and private; and if any crime has been committed, or murder done, or there is any dispute about succession or boundaries, they also decide it, determining awards and penalties: if any person or people does not abide by their decision, they ban such from sacrifice, which is their heaviest penalty. Those that are so banned are reckoned as impious and criminal; all men move out of their path and shun their approach and conversation, for fear they may get some harm from their contact, and no justice is done if they seek it, no distinction falls to their share. Of all these Druids one is chief, who has the highest authority among them. At his death, either any other that is pre-eminent in position succeeds, or, if there be several of equal standing, they strive for the primacy by the vote of the Druids, or sometimes even with armed force. These Druids, at a certain time of the year, meet within the bordes of the Crnutes, whose territory is reckoned as the centre of all Gaul, and sit in conclave in a consecrated spot. Thither assemble from every side all that have disputes, and they obey the decisions and judgments of the Druids. It is believed that their rule of life was discovered in Britain and transferred hence to Gaul; and to-day those who would study the subject more accurately journey, as a rule, to Britain to learn it.
"14 The Druids usually hold aloof from war, and do not pay war-taxes with the rest; they are excused from military service and exempt from all liabilities. Tempted by these great rewards, many young men assemble of their own motion to receive their training; many are sent by parents and relatives. Report says that in the schools of the Druids they learn by heart a great number of verses, and therefore somee persons remain twenty years in training. And they do not think it proper to commit these utterances to writing, although in almost all other matters, and in their private and public accounts, they make use of Greek letters. I believe that they have adopted the practice for two reasons - that they do not wish the rule to become common property, nor those who learn the rule to rely on writing and so neglect the cultivation of the memory; and, in fact, it does usually happen that the assistance of writing tends to relax the diligence of the student and the action of the memory. The cardinal doctrine which they seek to teach is that souls do not die, but after death pass from one to another; and this belief, as the fear of death is thereby cast aside, they hold to be the greatest incentive to valour. Besides this, they have many discussions as touching the stars and their movement, the size of the universe and of the earth, the order of nature, the strength and the powers of the immortal gods, and hand down their lore to the young men." (Caesar The Gallic War VI.13-14)
Caesar later informs us;
"The whole nation of the Gauls is greatly devoted to ritual observances, and for that reason those who are smitten with the more grievous maladies and who are engaged in the perils of battle either sacrifice human victims or vow to do so, employing the Druids as ministers for such sacrifices. ..." (Caesar The Gallic War VI.16)
The act of ritual human sacrifice among the Gauls is alluded to in the works of the Roman historian Gaius Suetonius Tranquillus, who writes;
"He [Claudius] utterly abolished the cruel and inhuman religion of the Druids among the Gauls, which under Augustus had merely been prohibited to Roman citizens; ..." (Suetonius The Lives of the Caesars - Claudius XXV.5.)
The famous passage from the poet rival of the emperor Nero is now available on a separate page:
"Those who think that philosophy is an invention of the barbarians explain the systems prevailing among each people. They say that the Gymnosophists and Druids make their pronouncements by means of riddles and dark sayings, teaching that the gods must be worshipped, and no evil done, and manly behaviour maintained."
"Nor is the practice of divination disregarded even among uncivilised tribes, if indeed there are Druids in Gaul - and there are, for I knew one of them myself, Divitiacus,¹ the Æduan, your guest and eulogist. He claimed to have that knowledge of nature which the Greeks call 'physiologia,' and he used to make predictions, sometimes by means of augury and sometimes by means of conjecture."
The primary sources quoted in the body of this page are: The Gallic War by Gaius Julius Caesar, translated from Latin by H.J. Edwards, The Lives of the Caesars by Gaius Suetonius Tranquillus, translated from Latin by J.C. Rolfe.