Eighteenth-century England was a land of profound contradiction. On the one hand it exhibited the spirit of the Age of Reason, with the intellects of Alexander Pope, Adam Smith, and Samuel Johnson flourishing in Augustan calm and elegance. But on the other it was a Hogarthian caricature come to life, a world of crime, disease, and squalor, where life was cheap and visitors to English cities half expected to be robbed, raped, or murdered upon arrival--and...