DRUIDS, n. Priests and ministers of an ancient Celtic religion which
did not disdain to employ the humble allurement of human sacrifice.
Very little is now known about the Druids and their faith. Pliny says
their religion, originating in Britain, spread eastward as far as
Persia. Caesar says those who desired to study its mysteries went to
Britain. Caesar himself went to Britain, but does not appear to have
obtained any high preferment in the Druidical Church, although his
talent for human sacrifice was considerable.
Druids performed their religious rites in groves, and knew nothing
of church mortgages and the season-ticket system of pew rents. They
were, in short, heathens and -- as they were once complacently
catalogued by a distinguished prelate of the Church of England --
-- Ambrose Bierce, "The Devil's Dictionary"