An Essay on the Development of Christian Doctrine

John Henry Cardinal Newman begins the Essay by defining how true developments in doctrine occur. He then delivers 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 emphasizes that thoughout the entire life of the Church this law of development has been in effect and safeguards the faith from any real corruption.

Ker concludes that, "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."