This detailed historical study focuses on Protestant natural law theories in the early German Enlightenment (explicitly excluding the French and British sectors) and traces their influence, or fate, through Kant. Despite its title, it is more than a specialist tome devoted to an historically isolable development, and it is not merely a subsidiary, underlaborer's attempt to recount the prehistory of Kant's achievement. Rather, by tracing several important background currents through the period concerned, Hochstrasser illuminates the odd historical fact that German enlighteners at the end of this span knew or thought so little of those at its beginning. The central topics are eclecticism; the so-called “histories of morality” that were part of its self-conscious legitimation method; the rationalism-voluntarism split in early modern natural law; and the associated distinction among moral philosophy (ethics), natural (positive) law, and international law (ius gentium) that developed out of these debates.