Karl Hefele's 'Conciliengeschichte' was one of the most significant works of Catholic historical scholarship in the nineteenth century. William Clark's translation presents the first two and a half volumes of Hefele's study, up to the Second Council of Nicaea (the German original is nine volumes, through the year 1536). This study marked a new stage in the study of conciliar action. It is universally admired for the breadth of its survey of the field, and for the relatively complete use of its material and unprejudiced historical attitude. -August Hegler and Karl Holl As one of the most detailed and thorough works on church history, it has attained a prominent place in the learned literature of our time. -Franz Xaver von Funk Karl Joseph Hefele (1809-1893), Roman Catholic prelate and church historian. Hefele followed his teacher Mohler at Tubingen in 1836, where he remained until his election as bishop in 1869. His edition of the 'Apostolic Fathers' was well respected and went through several editions. His work on the Epistle of Barnabas led the way to a more correct appreciation of the ancient document. But it is his work on the councils of the church for which he is most known.