The fundamental idea of the book is not unique, as is often claimed, but resulted from reflection over the origin of the Indians. To find a portion of humanity in isolated America was thought-provoking. Of various theories that of Hebraic origin was most common, fitting in best with the biblical ethnology of the time. It had been advocated by early Spanish priests, by a Jewish rabbi in 1650, and by many prominent men, among them Roger Williams, William Penn, and Jonathan Edwards. Five years before the publication of the Book of Mormon, Ethan Smith's View of the Hebrews or the Tribes of Israel in America was being sold, and many other writers advocated the same proposition.