At that time, the books were treated as forbidden books that never allowed to be taken out of the house, which even a high-caliber disciple was not allowed to browse and therefore these books were called book of Absolute secrecy.
当時この本は平田家では門外不出の厳禁本であり高弟でも閲覧する事を許されなかった極秘本といわれていた。