In G. K. Chesterton&s The Man Who Was Thursday, we encounter that intriguing individual, the philosophical policeman. His job is at once bolder and more subtle than that of ordinary policemen. Rather than arresting thieves or common or garden criminals, he goes to ‘artistic tea-parties to detect pessimists’, he reads books of sonnets to discover crimes about to be committed, he traces ‘the origin of those dreadful thoughts that drive men on at last to intellectual fanaticism and intellectual crime’.