An Essay on the Development of Christian Doctrine, reprinted here from the 1888 imprint in a handsome new papaerback edition, "is rightly regarded as one of the most seminal theological works ever to be written..., "says Ian Ker in the foreword. "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 with a definition of devleopment, pointing out that the real problem is how to distinguish true developments from corruptions and decays. He then goes on to a sweeping consideration of the growth and development of doctrine in the Catholic Church, from the time of the Apostles to Newman's own era. He demonstrates that the basic "rule" under which Christianity proceeded through the centuries is to be found in the principle of development, and emphasized that throughout the entire life of the Church this law of development has been in effect and safeguards the faith from any real corruption.. Ker points out, "In conclusion, we may say that the Essay is not only the starting point for the study of doctrinal development, but so far as Catholic theology is concerned, it is still the last word on the subject, to the extent that no other theologian has yet attempted anything on the same scale or of similar scope....But even if the Essay was not one of the great theological classics, it would still be of enduring interest for two reasons. First, it is one of the key intellectual documents of the nineteenth century, comparable to Darwin's Origin of Species, which it predates by over a decade. Second, if this were the only book of Newman to survive, its rhetorical art and style would surely place him among the masters of English prose."