The 'terrible mistake' was the contemporary utilitarian philosophy, expounded in Hard Times (1854) as the Philosophy of Fact by the hard-headed disciplinarian Thomas Gradgrind. But the novel, Dickens's shortest, is more than a polemical tract for the times; the tragic story of Louisa Gradgrind and her father is one of Dickens's triumphs. When Louisa, trapped in a loveless marriage, falls prey to an idle seducer, the crisis forces her father to reconsider his cherished system. Yet even as the development of the story reflects Dickens's growing pessimism about human nature and society, Hard Times marks his return to the theme which had made his early works so popular: the amusements of the people. Sleary's circus represents Dickens's most considered defence of the necessity of entertainment, and infuses the novel with the good humour which has ensured its appeal to generations of readers.