On Newman’s book:
An Essay on the Development of Christian Doctrine, reprinted from the 1888 imprint, “is rightly regarded as one of the most seminal theological works ever to be written,” states Ian Ker in his 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 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.”
There are few other books that so effectively distinguish Catholic doctrine from various other ecclesial bodies, whether Protestant or Orthodox.
Regarding its style, here’s the end of chapter six:
If then there is now a form of Christianity such, that it extends throughout the world, though with varying measures of prominence or prosperity in separate places; —that it lies under the power of sovereigns and magistrates, in various ways alien to its faith; —that flourishing nations and great empires, professing or tolerating the Christian name, lie over against it as antagonists; —that schools of philosophy and learning are supporting theories, and following out conclusions, hostile to it, and establishing an exegetical system subversive of its Scriptures; —that it has lost whole Churches by schism, and is now opposed by powerful communions once part of itself; —that it has been altogether or almost driven from some countries; —that in others its line of teachers is overlaid, its flocks oppressed, its Churches occupied, its property held by what may be called a duplicate succession; —that in others its members are degenerate and corrupt, and are surpassed in conscientiousness and in virtue, as in gifts of intellect, by the very heretics whom it condemns; —that heresies are rife and bishops negligent within its own pale; —and that amid its disorders and its fears there is but one Voice for whose decisions the peoples wait with trust, one Name and one See to which they look with hope, and that name Peter, and that see Rome; —such a religion is not unlike the Christianity of the fifth and sixth Centuries.