This text explores the Enlightenment as a movement emphasizing the light of reason, emerging as a necessary reaction to the lack of critical thinking and obscurantism of previous eras. It underscores that the Enlightenment sought not only to understand the world but to guide life and society through rational principles, exemplified by the sweeping Josephine reforms. Central to this era was the development of a critical spirit, reaching its peak in Kant’s philosophy where reason critiques itself as the only instance available to humanity for navigating existence. While critics such as Emanuel Rádl highlighted its potential for shallowness, ideology, or cynicism, the movement’s lasting legacy lies in its transformation of the spiritual atmosphere and its promotion of freedom and scientific methodology. These developments significantly influenced the humanities and even theology, fostering an environment of tolerance grounded in rational discourse. The author argues that contemporary scientific debate is unthinkable without the foundations laid by the Enlightenment. Although modern thought has moved beyond certain naive assumptions of that period, the commitment to reason and critical thinking remains a cornerstone of modern intellectual life.