On his 19th birthday Orson Pratt is baptized into the Mormon Church by his brother Parley. He becomes one of the first apostles, almost commits suicide after finding that Joseph Smith had propositioned his wife, is excommunicated, rebaptized, fulfills 11 missions for the church. He teaches himself mathematics, physics and astronomy and publishes textbooks on advanced algebra. He differs in doctrinal matters with president Brigham Young and is threatened with disciplinary action over it but Pratt's views are later adopted by the Church while Young's are labeled as "heresy." Before he dies in 1881 Orson Pratt had been a Mormon longer than any other person.
[On This Day in Mormon History, http://onthisdayinmormonhistory.blogspot.com]