A secret cult which dealt with the magic arts practised in ancient Gaul and the British Isles.
The Druids as priests, diviners, judges, teachers, physicians, astronomers, and philosophers, formed a class apart from and above the people whom they kept in subjection.
Their chief duties were to teach youths by means of a system of oral education, and to preside over the traditional religious ceremonies.
They had special regard for the oak and mistletoe, and practised magic rites.
Although there is evidence that they did not originate the act of human sacrifice in Gaul, it was practised there.
The Druids lost their power after the Roman conquest of Gaul and Britain and gradually disappeared, not however through any organized persecution.
In the sagas of Ireland, Druids do not appear as a distinct and powerful class, but as learned men and, frequently, as advisers of the king.
New Catholic Dictionary