A person can think of them as Priests if they wish to, it's an easy word to put into a context, but prior to the Roman invasion of the Islands inhabited by the clans of the Britons, Druids were an influential class that likely crossed the boundaries between tribes by owing their allegiance not to the earthly passions of Paramount Chiefs but to a set of ideas that dominated the dream world of Island Celts. Druids had no written word, it was down to memory and by some reckoning knowledge sufficient to be considered a Druid required a good twenty years of diligence. The no writing stuff down of course was a problem for future understanding, but it was more likely a union rule for Druids and if I think about it anything this side of a balance sheet when it gets written down can become red faced dogma for the Nitpick.
The Romans, in their wars against the Celts, considered them extraordinarily
fearless and after the conquest of Celtic territory the Romans went to extreme
lengths to persecute Druids, attempted to obliterate the memory of them.
Naturally enough as the world moved on into the Industrial Revolution, the Age
of Reason and so on, a certain romanticism grew around the idea of Druids. But
Wizards and Witches, good and bad fairies, a oneness with nature perhaps, along
with interesting outfits never quite undid a Roman and Christian Church
propaganda that had nothing nice to say about Druids. Druids believed that when
you died you went underground where you hung around for a bit and you returned
again as another person. And if there is a point, the Witch of Ithaca was a
Druid. Call her the Last Druid of The Silures, she becomes isolated a lonely,
call her a Witch and she has a place in the way we think.