Druids, the priestly and intellectual class of the ancient Celts, ruled on civil and criminal proceedings, performed religious ceremonies, preserved tribal history and lore, and educated the young.

Druids served as an intellectual caste of judges, prophets, and teachers at the top of the social structure of ancient Celtic culture. Because there are no written extant Druidic texts, it is difficult to be exact about either documenting the dating of their influence or even specifically defining their philosophies and ethical worldview. Indeed, it was reportedly the tradition that, although the Celts were familiar with the Greek alphabet and used it for business purposes, Druidic doctrine had to be transmitted orally, a process in which young Druid priests would commit doctrine to memory over a period of twenty years or more. As a result, contemporary information about the Druids comes from Greek and Roman commentators, while information from within the Celtic tradition comes from the post-Christian era. In both cases, therefore, information about Druidism comes from the opponents of Druidism.

The etymology of the word druid is contested. The second element is accepted as deriving from wid-, an Indo-European root connoting wisdom, knowledge, and (oracular) sight. The first element comes from an Indo-European root deru, which has connotations of hardness, firmness, and steadfastness, but opinions differ as to whether the dru- in “druid” comes from forms of the root meaning “truth” or from a form meaning “tree,” especially the oak (derw in Welsh). Although the etymology of Druids as purveyors of “oak wisdom” was long accepted, recent opinion has veered toward “true knowledge” as the more probable meaning.

Any contemporary understanding of the Druids and their legacies relies on archaeological evidence (including votive pits, sculpture, tools, jewelry, temples, and fortresses) as well as the writings of Greek and Roman chroniclers. Most classical writing on Druids derives from Posidonius, a Greek philosopher from Syria who lived in the first century b.c.e. and wrote of his travels among the Celts. However, his own writings are lost and all that survives is quotations in the works of later writers such as Strabo, Diodorus Siculus, and Julius Caesar, who, although he was personally acquainted with the Druid Divitiacus, as he relates in his Comentarii de bello Gallico (52-51 b.c.e.; Commentaries, 1609), apparently felt that Posidonius’s work was more authoritative than his own experience.

In continental Gaul (modern-day France), Druids were exempt from taxes and were not required or expected to provide military service, although in practice there were exceptions. More often they served as sage counselors to the tribal chief and war-leader. They were the teachers of noble Celtic children as well as of Druids in training. Druids adjudicated both criminal and civil law disputes; the harshest sentence they could inflict was to ban a person from participating in sacrifices, thereby turning him into a nonperson. The Druids officiated at these sacrifices to the gods, which were said to include the sacrifice of humans. The latter practice seems to have created conflict with the Romans soon after initial contact because both Tiberius and Claudius report the Roman banishment of the Druids as a result of such profane superstitions. However, it is an open question whether human sacrifice was actually practiced, either in the past or at the time of Roman contact, or whether it was a calumny aimed at undercutting the Druids’ political opposition to Rome. It is nonetheless notable that the Romans quickly outlawed Druidism, while Roman practice generally was to annex new gods and practices into its own pantheon rather than outlawing them.

Druidic teaching seems to have deemphasized the importance of the moment of death. Druids believed that the human soul is immortal and that the universe is indestructible (although they believed that it was periodically consumed in a ritual cleansing by fire and water alternately). The animal or human sacrifice was used not only to ensure the fertility or effectiveness of the ritual but also because the very manner and movement of the death of the sacrifice demanded priestly interpretation: the pattern of the blood flowing from the mortal wound or the movement made in the victim’s death throes was noted and interpreted by the Druid priests.

Pliny the Elder notes in his Naturalis historia (77 c.e.; Natural History, 1938-1963) that the Druids were nature-healers who employed liberal amounts of mistletoe and other medicinal herbs in their rituals. (Pliny is the only major classical source to emphasize the ritual importance of oak trees in Druidic ritual, a connection that Robert Graves made the centerpiece of his poetically inspired but historically suspect White Goddess, 1948.) Pliny described elaborate formulae and taboos governing how particular ingredients should be collected—samolus should be plucked with the left hand only; selago should be picked with the right hand stretched through the left sleeve of a white robe—and even the particular phases of the moon during which such collection should occur.

Druidic belief and practice were most likely in decline in Gaul by the time of Julius Caesar’s victory over the Gaulish chieftain Vercingetorix at Avaricum in 52 b.c.e. The religion persisted longer in Britain, which Caesar reported was the birthplace of Druidism and the source of its truest doctrine. Reports of Druids are common throughout the next century, until the watershed point at the end of classical Druid history, the Roman defeat of the Celts at Anglesey in 61 c.e. which destroyed the Druidic stronghold.

Over the next four centuries, the Celts of Britain and Gaul practiced a religion that mixed elements of native belief with Roman religion. The temple at Bath in southern England is a good example of this later trend: The hot springs and their tutelary goddess Sulis had long been worshiped by the Celts, and with the advent of the Romans, Sulis became Sulis Minerva and the springs became the focal point of a magnificent Roman temple and healing spa. In Ireland, which never fell under Roman rule, Druids maintained their positions as teachers, counselors, judges, and poets until the advent of Christianity, and often appear in early saints’ lives as magic-working opponents of the holy men and women.

An artist’s conception of Druid worship in ancient Gaul.

(F. R. Niglutsch)

Druidic practice was moribund throughout the Middle Ages, but the late Renaissance in France and England rekindled a fascination with the mystery and antiquity of the nature-loving Druids, in large part in England because of the writings of William Stukeley (1687-1765). Stukeley’s archaeological volumes Stonehenge, a Temple Restored to the British Druids (1740) and Avebury (1743) popularized the Druids in the English-speaking world as philosopher-sages responsible for these magnificent megalithic monuments, whose religion “was so extremely like Christianity, that in effect, it differed from it only in this; they believed in a Messiah who was to come into the world, as we believe in Him who has come.”

The Druids and their place in the Celtic pre-Christian past continue to enjoy significant attention in contemporary Western societies. In the popular imagination, reconstructed Druidic religions in various forms have been practiced since Stukeley’s time. The Druids’ role as public intellectuals was adopted by Celtic nationalist movements beginning in the nineteenth century, and latter-day Druids preside over the Welsh National Eisteddfod, a yearly artistic and cultural festival, and similar organizations in Cornwall and Brittany.

More important, while early Christians repressed the particulars of Druidic religious rituals and doctrines, the monks of Ireland, Scotland, Wales, Brittany, and Cornwall preserved much of the literary and historical lore that the Druids had maintained in oral tradition. Although the religious functions of the Druids were eliminated, their roles as judges, lawyers, counselors, teachers, doctors, poets, and historians remained.

• Brunaux, Jean Louis. The Celtic Gauls: Gods, Rites, and Sanctuaries. Translated by Daphne Nash. London: Seaby, 1988. Presents the archaeological evidence for Druidic religion on the Continent in a clear and insightful manner.
• Cunliffe, Barry. The Ancient Celts. New York: Oxford University Press, 1997. This comprehensive overview of Celtic culture includes significant chapters on history, community, religion, and the enduring legacy of Druidic culture in modern society. Includes many black-and-white and color plates with scholarly editing.
• Freeman, Philip. War, Women, and Druids: Eyewitness Reports and Early Accounts of the Ancient Celts. Austin: University of Texas Press, 2002. Collects primary source material on Druids from the classical world. Given the amount of fantasizing focused on Druidism, it is useful to read the original sources of their contemporaries.
• Green, Miranda J. The World of the Druids. New York: Thames and Hudson, 1997. Provides an introduction to the world of the Druids via Welsh and Irish myths, including excellent chapters on Celtic society, derived principally through writings of early Roman invaders and archaeological evidence.
• Hutton, Ronald. The Pagan Religions of the Ancient British Isles: Their Nature and Legacy. Cambridge, Mass.: Blackwell, 1991. A well-researched history that aims to dispel many of the myths about Britain’s pagan heritage. Chapters 5-7 deal with the development of Druidism and its confrontation and accommodation with Roman and Christian religion.
• Kendrick, T. D. Druids and Druidism. 1960. Reprint. Mineola, N.Y.: Dover, 2003. One of the classic works on Druidism, addressing the information about and opinions of Druidism prevalent in the Greek and Roman worlds and assessing the archaeological evidence of religious practices. Although dated, Kendrick’s analysis is sober and insightful.
• Ó Hógáin, Dáithi. The Sacred Isle: Belief and Religion in Pre-Christian Ireland. Rochester, N.Y.: Boydell, 1999. Written by a well-known folklorist, this book attempts to reconstruct the religious beliefs of Irish Druidism by making connections between medieval Irish mythological narratives and modern folklore, archaeological remains, and the comparative anthropology of religion.

Boudicca; Vercingetorix. Druidism