This impressively-edited volume makes available a fully-annotated edition of letters between Albrecht Ritschl and Adolf Harnack, the bulk of which are located in the Berlin State Library, ‘Stiftung Preussischer Kulturbesitz’. Weinhardt's close analysis of the often densely-worded correspondence between two of the towering figures of late nineteenth-century German theology will serve as an important resource for those theologians and historians seeking to understand the key personalities responsible for the formation of ‘liberal’ theology in the Wilhelmine period. The editor's introduction, which runs to well over a hundred pages, serves to contextualise the two theologians and to summarise the leading contours of their thought, as well as to highlight their similarities and differences, which are especially apparent in Harnack's critique of Ritschl's introductory volume, Unterricht in der christlichen Religion. (Weinhardt helpfully reprints Harnack's review of Ritschl's book from the Theologische Literaturzeitung.) Weinhardt's scholarship and detailed understanding of the so-called Ritschlian School reveal some of the tensions between teacher and ‘pupil’ (although this term is misleading when applied to Harnack since he had never studied with Ritschl). Harnack's major differences from Ritschl were shared with some of Ritschl's other students, many of whom, such as Ernst Troeltsch, had studied with Ritschl in Göttingen: what emerges through the volume is a fundamental conflict between the twin enlightenment strands of rationalism and supranaturalism which were understood differently by the two men and which dominated so much theological thought through the nineteenth century. Despite differences, however, the tone of the letters is personal, affectionate and familiar if also rather formal: much of the correspondence covers their families, their health, their reading of third parties and their reaction to church and educational politics. The two men met on a number of occasions – twenty-three meetings are listed – and also recounted their many meetings with others. As Harnack developed his own theological voice through the 1870s and '80 s when he was mainly in Giessen (before being called to Marburg in 1886 and then to Berlin in 1888 shortly before Ritschl's death the following year), so he became increasingly engaged in the study of history and of the early Church. Weinhardt also makes available a number of other texts, including Ferdinand Kattenbusch's recollections of Harnack at Giessen, and a list of Harnack's lectures in Leipzig, Giessen and Marburg.