Immanuel Kant (1724-1804) was born in Königsberg in what was then the Kingdom of Prussia (where he would also die), the fourth of nine children of a poor harness-maker. His parents were sincere pietists, pietism being a reform movement within the Lutheran Church emphasizing biblical doctrine, personal piety, and earnest Christian living. It also emphasized the sovereignty of conscience, and that would have a lasting effect on Kant’s moral thinking. At 45, he was finally appointed a full professor (of logic and metaphysics) at the University of Königsberg, which shifted him from his earlier focus on mathematics and physics. His major works are the three great critiques: The Critique of Pure Reason (1781, revised 1787) on metaphysics and epistemology (presenting transcendental idealism as the reconciliation of rationalism and empiricism), The Critique of Practical Reason (1788) on ethics, and The Critique of Judgment (1790) on aesthetics and teleology.

Prussia was an enlightened state under Frederick the Great, but when Frederick William II became king in 1786, his minister Wöllner attempted to end religious toleration with regard to the enlighteners. Kant responded with Religion within the Limits of Reason Alone (1793), an essential text in the development of liberal Protestantism. Profoundly influenced by Rousseau, Kant was a committed Enlightenment thinker who nevertheless moved European thought towards Romanticism. He summed up the impulse of his thinking, “Two things fill the heart with ever-increasing wonder and awe, the more often and more steadily we meditate upon them: the starry heavens above me and the moral law within me.”