American mathematician and religious leader who was an original member of the Quorum of the Twelve Apostles of the Church of Jesus Christ of Latter Day Saints.
Just read this in the process of producing a Project Gutenberg edition that should hopefully be out soon. It's notable as the earliest published account of Joseph Smith's First Vision. It also has some detail on his vision of Moroni that I hadn't previously encountered and contains a presentation of the doctrine of the Church of Jesus Christ of Latter-Day Saints that was partly used to develop the Articles of Faith.
Given that it's only 36 pages long (originally published as a pamphlet), well worth a read.