BHR says JS could have used creative imagination to write BOM.
B.H. Roberts, "A Book of Mormon Study," Box 19, Folder 14, B.H. Roberts Papers, Marriott Special Collections
In the light of this evidence, there can be no doubt as to the possession of a vividly strong, creative imagination by Joseph Smith, the Prophet, An imagination, it could with reason be urged, which, given the suggestions that are to be found in the "common knowledge" of accepted American Antiquities of the times, supplimented by such a work as Ethan Smith's "View of the Hebrews", would make it possible for him to create a book such as the Book of Mormon is.