Aradia, or the Gospel of the Witches

From Wikipedia:
Aradia, or the Gospel of the Witches is an 1899 book by Charles Godfrey Leland. The book is an attempt to portray the beliefs and rituals of an underground religious witchcraft tradition in Tuscany that, Leland claimed, had survived for centuries until his discovery of its existence in the 1890s. Scholars have disputed the veracity of this claim. Still, the book has become one of the foundational texts of Wicca and Neopaganism.

The text is a composite. Some of it is Leland's translation into English of an original Italian manuscript, the Vangelo (gospel). Leland reported receiving the manuscript from his primary informant on Italian witchcraft beliefs, a woman Leland called "Maddalena". The rest of the material comes from Leland's research on Italian folklore and traditions, including other related material from Maddalena. Leland had been informed of the Vangelo's existence in 1886, but it took Maddalena eleven years to provide him with a copy. After translating and editing the material, it took another two years for the book to be published. Its fifteen chapters portray the origins, beliefs, rituals and spells of an Italian pagan witchcraft tradition. The central figure of that religion is the goddess Aradia, who came to Earth to teach the practice of witchcraft to peasants in order for them to oppose their feudal oppressors and the Catholic Church.

Leland's work remained obscure until the 1950s, when other theories about, and claims of, "pagan witchcraft" survivals began to be widely discussed. Aradia began to be examined within the wider context of such claims. Scholars are divided, with some dismissing Leland's assertion regarding the origins of the manuscript, and others arguing for its authenticity as a unique documentation of folk beliefs. Along with increased scholarly attention, Aradia came to play a special role in the history of Gardnerian Wicca and its offshoots, being used as evidence that pagan witchcraft survivals existed in Europe, and because a passage from the book's first chapter was used as a part of the religion's liturgy. After the increase in interest in the text, it became widely available through numerous reprints from a variety of publishers, including a 1999 critical edition with a new translation by Mario and Dina Pazzaglini.