Members of the Church of Jesus Christ of Latter-Day Saints, which was founded in New York in 1830 by Joseph Smith (1805–44). He claimed to have discovered, through divine revelation, the ‘Book of Mormon’, relating the history of a group of Hebrews who migrated to America c.600 bc. This work is accepted by Mormons as Scripture along with the Bible. A further revelation led him to institute polygamy, a practice that brought the Mormons into conflict with the Federal Government and was abandoned in 1890. Smith was succeeded as leader by Brigham Young (1801–77), who moved the Mormon headquarters to Salt Lake City, Utah, in 1847. Mormon teaching is strongly adventist; the movement has no professional clergy, self-help is emphasized, and tithing and missionary work are required of its members.