An Essay on the Development of Christian DoctrineAn Essay on the Development of Christian Doctrine, reprinted from the 1878 edition, is rightly regarded as one of the most seminal theological works ever to be written, states Ian Ker in his foreword to this sixth edition. It remains, Ker continues, "the classic text for the theology of the development of doctrine, a branch of theology which has become especially important in the ecumenical era. John Henry Cardinal Newman begins the Essay by defining