According to Joseph Smith's own story, when he was 17 years old, he was visited by an angel named Moroni. Moroni told him about a really old book written upon Golden Plates. It was buried in a hill. A few years later, Joseph said that he received those plates and translated them into the book that today is call The Book of Mormon. He instructed a man named Martin Harris to write down the words that he said was a translation of the plates. He said Moroni gave him seer stones which would help him translate the golden plates. Harris took home the pages and told his wife all about what had happened, but she did not believe him. Those pages were lost, and Joseph told Martin that God was very angry with them. Eventually, Joseph was allowed to translate the rest of the book, with help from Oliver Cowdery instead of Martin Harris.