There are philosophers whose ideas remain confined to academic circles, debated by specialists and forgotten by the wider culture. Then there are philosophers whose insights become so embedded in how we understand ourselves that their influence becomes invisible, absorbed into the very structure of modern thought. Schopenhauer belongs firmly to the second category. His fingerprints are all over twentieth-century psychology, philosophy, and culture, yet most people who have absorbed his ideas have never read a word of his work. The reason for this is simple: Schopenhauer’s core insights about the unconscious, the irrationality of desire, the centrality of suffering, and...