Examining Brigham Young's legacy requires an understanding of his raw ambition and religious zeal. A formidable leader in both his church and country, Young's abilities coincided with the colonizing zeitgeist of nineteenth-century America. Thus, by 1877, some 400 Mormon settlements spanned the western frontier from Salt Lake City to outposts in Idaho, Nevada, Arizona, Wyoming, and California. As prophet of the LDS Church and governor of the proposed State of Deseret, Young led several campaigns for Utah statehood while defending polygamy and local sovereignty. His skillful and authoritarian leadership led historian Bernard de Voto to classify him as an "American genius," responsible for turning Joseph Smith's visions "into the seed of life." Young's diaries and journals reveal a man dedicated to his church, defensive of his spiritual and temporal claims to authority, and determined to create a modern Zion within the Utah desert. Editor George D. Smith's careful organization and annotation of Young's personal writings provide insights into the mind of Mormonism's dynamic church leader and frontier statesman.