Complex sentence: Leonard John Nuttall was the private secretary for Brigham Young and a member of the Council of Fifty who kept a detailed journal of the early history of the Church of Jesus Christ of Latter-day Saints.
Split into simpler sentences: Leonard John Nuttall was the private secretary for Brigham Young and a member of the Council of Fifty. He kept a detailed journal of the early history of the Church of Jesus Christ of Latter-day Saints.