How can doctrines be made intelligible within the context of our modern world? This book throws new light upon Lonergan's response to this challenge in his presentation of the functional specialty, systematics, within his Method in Theology. This book primarily aims to present a thorough understanding of systematics function. We first investigate systematics specific function as a promotion of understanding, of the mysteries of faith. We then examine the need for, and grounds of, this functional specialty and we place systematics in relation to the other functional specialties within Lonergan's Method in Theology. Of special concern to this work is an investigation of what Lonergan could have meant by explaining systematics function by reference to the statement of the First Vatican Council, that human reason can attain an understanding of the mysteries both by analogy with what human reason naturally knows and by the interconnection of the mysteries with each other and with humanity's last end. To make systematics function more intelligible, we investigate the conditions prevailing in Catholic theology that prompted Lonergan to develop his theological method, assess the value and place of systematics, and evaluate Lonergan's presentation of systematics in relation to the goals he set himself in developing a theological method.