The major writings, teachings, and thoughts of Elder John A. Widtsoe have been readily available to Latter-day Saints for more than half a century now. What has not been readily available, however, is an overview, compilation, or compendium of those writings, teachings, and thoughts in a topical guide with A to Z format. As a result, to fully grasp any one teaching of Elder Widtsoe required reading through all of his numerous writings to capture the highly nuanced insights and clarifications that were often a pervasive part of his own scientific and theological methodology. Out of sheer frustration with this laborious process, compiler David Martin Call began a ten-year labor of love bringing together the material that has evolved into this doctrinal compendium, which features the most salient teachings of Elder Widtsoe-a master teacher, a scientist, and an apostle in The Church of Jesus Christ of Latter-day Saints.