Martin Mulsow’s seismic reinterpretation of the origins of the Enlightenment in Germany won awards and renown in its original German edition, and now H. C. Erik Midelfort's translation and abridgement makes this sensational book available to English-speaking readers. Scouring manuscript collections across northern Europe, Mulsow studied the writings of countless hitherto unknown radical jurists, theologians, historians, and dissident students who pushed for the secularization of legal, political, social, and religious knowledge. Often their works circulated in manuscript, anonymously, or as clandestinely published books. In Enlightenment Underground, Mulsow shows that even in the late seventeenth century some thinkers in Germany ventured to express extremely dangerous ideas, but did so as part of a secret underground. This landmark book overturns stereotypical views of the early Enlightenment movement in Germany as cautious, conservative, and moderate, and replaces them with a new portrait that reveals an early Enlightenment far more radical, unintended, and puzzling than previously suspected.