Robert Graves' somewhat bizarre "Historical Grammar of Poetic Myth", in which he combines Classical and British
mythology with his own imaginary
religion to outline a belief system centered around a Goddess of Poetry.
As its purpose is unclear and its writing style implies that it is a work of serious history, The White Goddess has often been (rightly) derided as ahistorical and inaccurate in its depiction of ancient religion. However, Graves did not intend for it to be taken as a factual account, but rather as a work of fiction dealing with poetry and its role in history. (Or maybe not - he later said "It's a crazy book and I didn't mean to write it.")
The White Goddess is the source of many Wiccan beliefs.