J.G. Hamann (1730-88) was a solitary and idiosyncratic thinker who lived a life of poverty and neglect. He was admired by Herder, Goethe, and later by Kierkegaard, and Berlin's account shows how original Hamann's thinking was and how important it is to our times. He was the first opponent of the Enlightenment, the father of modern irrationalism, and a crucial forerunner to romanticism and, much later, existentialism. In this book, Berlin demonstrates the power of Hamann's insights into human knowledge, the relationship between language and thought, God and man, and creative genius.