Although Newman certainly did not write the Essay on the Development of Christian Doctrine with the intention to do systematic theology, his ten principles serve as a framework for ordering the content of the essay with reference to Newman's other works. The result in this present book is a systematic analysis of the theological themes considered by Newman throughout his writing career. Newman's writings were circumstantial in nature, written in response to controversies or needs of the moment. Nevertheless, he was able to shed light on those specific situations by appealing to timeless theological insights. The originality of this book consists in placing these insights in a systematic context. The arrangement is structured as a fundamental theology, following the usual discourse on God's revelation and faith as a response, with a brief intermediate exposition of fundamental Christology and ecclesiology. In order to give it Newman's own imprint, the author has provided only brief introductions or comments, as well as references to other authors, giving priority to Newman's own texts. In this way the work serves as an introduction to the thought and even to the life of John Henry Newman, whose literary style denotes the union of theological questions with a living faith.