I've heard about the "Delphic Oracle" - and presume it's the same one that RLynn write about. She figues in both the book "I, Claudius" by Robert Graves and in the TV series based on the book. The Emperor Claudius wrotes a "warts and all" history of his family after the Oracle told him that it would survive for over a 1000 years before being discovered to reveal the truth.