0Saint Thomas Aquinas's masterwork, the Summa theologiae, can be daunting to beginners. This volume by an expert on Aquinas's theology offers an ideal introduction. It presents key selections from the Summa along with accessible commentary designed to provide background, explain key concepts, and walk readers through Aquinas's arguments. Previously published as Holy Teaching, this new edition has been fully revised and includes a substantial amount of new material. The book draws from the entire Summa and incorporates selections that focus on moral theology, providing a fuller picture of Aquinas's thought.