The Filioque: History of a Doctrinal Controversy is the first complete English language history of the filioque written in over a century. Beginning with the biblical texts and ending with recent agreements on the place and meaning of the filioque, this book traces the history of the doctrine and the controversy that has surrounded it. From the Greek and Latin fathers, the ninth-century debates, and the Councils of Lyons and Ferrara-Florence, to the twentieth- and twenty-first century-theologians and dialogues that have come closer than ever to resolving this contentious issue, A. Edward Siecienski explores the strange and fascinating history behind one of the greatest ecumenical rifts in Christendom.