The Book of Mormon is the name of a book, or division, in the larger Book of Mormon. This "inner" book has nine chapters. According to the text, the first seven chapters were written by the prophet Mormon and the last two by his son Moroni. These men were given a sacred charge to observe the destruction of their people for their wickedness and failure to repent; and to record their observations on metal plates which would be hidden until the Lord would reveal them to the world at a future time.