I have attempted to provide a report on a great adventure in the realm of thought. All the peoples of Western Europe participated in it. It developed with the slowness of a mass movement. Its unit of time is half a century. The report is the narrative of an episode in the emergence of reason. It shows how a particular direction of reason arises in a people due to the long groundwork of earlier epochs, how its theme slowly unfolds after its birth, how it celebrates its triumphs, how its influence even shapes the motives of human action, and how, ultimately, at the moment of its greatest success, its limits become apparent and once again call for creative imagination.