A keystone is the center stone at the crown of an arch; it keeps the other stones locked into place. If the keystone is removed, the arch will collapse.
The prophet Joseph Smith said, “I told the brethren that the Book of Mormon was the most correct of any book on earth, and the keystone of our religion, and a man would get nearer to God by abiding by its precepts, than by any other book.” President Benson has also told us that the Book of Mormon is the keystone of our religion, and he said that we should study it daily. In order to keep track of your reading of the Book of Mormon during this year, turn page, open staples, and carefully remove poster from magazine. Close staples. Cut picture section from bottom of poster. Hang poster up. As you finish reading each book in the Book of Mormon (by yourself or with your family), cut out the appropriate picture and glue it in the correct place on the poster. Younger children may wish to read only the italicized chapters each month. When you have finished the entire Book of Mormon (or the chapters), glue the keystone at the top of the arch.
Starting in the February 1988 Friend, you will find an activity page that will correspond with the reading you are to do for that month. Watch for this symbol each month.
“The Book of Mormon is the keystone of testimony. Just as the arch crumbles if the keystone is removed, so does all the Church stand or fall with the truthfulness of the Book of Mormon.”
President Ezra Taft Benson (Ensign, November 1986, page 6.)