Moses Mendelssohn has yet to receive an exhaustive treatment, a fate he shares with the entire epoch to which he belongs. That the scholarly treatment of the modern bourgeoisie still has not made use of the most important sources of its social constitution is a special problem and one, to be sure, which explains why Mendelssohn above all has not yet found his biographer. In and of itself, the Enlightenment is neither geographically nor temporally accessible as a unified movement. Its single universal characteristic is that it is everywhere the reflection of the rise of the bourgeois class. It is a rise which already bears mature fruit in England as it is being achieved in bloody turmoil in France and is transforming itself in Germany into an almost century-long defeat.