This synoptic essays examines critically the origins, development, decline, and historical significance of the European Enlightenment. It defines, firs, the essentials of Enlightenment thought and the historical conjuncture and mentality out of which it grew. It then shows hoe the Enlightenment could serve both as a weapon against the Old Regime and as a rallying cry of the ascendant bourgeoisie during its heroic age. Particular attention is paid to the dialectical relationship between the Enlightenment and the material order which it sought to transform and to the contradictions within Enlightenment thought and the social class whose interests it sought to justify. The underlying theme of this inquiry is the real and possible relevance of the Enlightenment tradition to contemporary Western society.