From Roman authors we know that the Druids were the religious leaders of Celtic Gaul and Britain and repositories of large bodies of oral tradition. They acted as magistrates, teachers, healers and lawgivers, with a detailed knowledge also of astronomy. They were augers and diviners, and could reinforce their authority with the threat of divine sanctions.
Britain was said to be the home of Druidism, where aspiring novices went to study. The Romans not only saw the Druids as the focal point for Celtic resistance but also viewed with horror their reported practice of human sacrifice. Strabo records that:
