In 1922, May Blackburn and her daughter, Ruth, began proclaiming themselves as the two witnesses of the Book of Revelation and assembled a collection of followers from Portland and Los Angeles, and later from around the country. Blackburn claimed that the angels Gabriel and Michael were dictating a book (initially dubbed "The Seventh Trumpet of Gabriel," but later changed to "The Great Sixth Seal") to her and her daughter that explained all the secrets of the universe. She promised that when the book was published, the Seventh Seal described in Revelation would be broken in heaven and an apocalyptic event would occur.
