In the 18th century the druid religion was actually resurrected, but with little documentary evidence for what they actually believed in, it's difficult to know how close to the original religion new druids are.
Documentary evidence is any evidence introduced at a trial in the form of documents. Although this term is most widely understood to mean writings on paper (such as an invoice, a contract or a will), the term actually include any media by which information can be preserved. Photographs, tape recordings, films, and printed emails are all forms of documentary evidence.