The greatness of John Henry Newman’s Essay on the Development of Christian Doctrine has been acknowledged many times since it was first published in 1845. Its international repute was secured by the beginning of the twentieth century; for example, the future Archbishop of Uppsala, Nathan Söderblom, writing on the modernist movement, described it and its author in 1910 as ‘the most significant theological work, written by England’s foremost theologian, and together with Leo XIII, the most important man in the Roman Catholic Church during the last century’. This estimation is confirmed by the impact Newman’s book has had on twentieth-century theology. One recent observer has judged that it is ‘significant, less for its positive arguments … [than] for its method of approach to the whole problem of Christian doctrine in its relation to the New Testament’. In other words, Newman’s book touches on a central topic of modern theology.