This volume contains studies on two of the most fascinating personalities in the academic world of the 20th century. In their common years in Heidelberg, both Weber and Troeltsch developed a research program in sociology of religion which was devoted to the analysis of the “cultural importance” of religion, in particular Protestant piety. Their common interest in an analytical explanation of religion as vital power (“Lebensmacht”), however, resulted in different and competing theoretical programs. The studies in this book explore the constellations of the two men’s lives and works.