This book is the first comprehensive study on Moses Mendelssohn’s (1729–1786) language philosophy. While guiding the reader throughhis œuvre, a new perspective is gained that brings Mendelssohn closer to the skeptical currents of Enlightenment. The dialectics of human and sacred language play a constitutive role for his language theory as well as for his aesthetics and metaphysics, and finally lead into the political idea of a just, social order. Thus, he developed an important alternative to monolingual, national language concepts.