Book excerpt: Originally published in German in 1936, The Natural Law is the first work to clarify the differences between traditional natural law as represented in the writings of Cicero, Aquinas, and Hooker and the revolutionary doctrines of natural rights espoused by Hobbes, Locke, and Rousseau. Beginning with the legacies of Greek and Roman life and thought, Rommen traces the natural law tradition to its displacement by legal positivism and concludes with what the author calls "the reappearance" of natural law thought in more recent times. In seven chapters each Rommen explores "The History of the Idea of Natural Law" and "The Philosophy and Content of the Natural Law." In his introduction, Russell Hittinger places Rommen's work in the context of contemporary debate on the relevance of natural law to philosophical inquiry and constitutional interpretation. Heinrich Rommen (1897–1967) taught in Germany and England before concluding his distinguished scholarly career at Georgetown University. Russell Hittinger is William K. Warren Professor of Catholic Studies and Research Professor of Law at the University of Tulsa.