Gotthold Ephraim Lessing (1729-81) stands as a key figure in German intellectual history, a bridge joining Luther, Leibniz, and German idealism. Despite his well-recognized importance in the history of thought, Lessing as theologian or philosopher of religion remains an enigmatic figure. Scholars refer to the "riddle" or "mystery" of Lessing, a mystery that has proved intractable because of his reticence on the subject of the final conclusions of his intellectual project. Toshimasa Yasukata seeks to unravel this mystery. Based on intensive study of the entire corpus of Lessing's philosophical...