With the Royal Navy ruling the waves, Queen Victoria safely on her throne, science explaining a confusing world, and British missionaries, explorers, and armies turning the map pink you’d think that the mid-19th-century English (or at least the upper classes) would be a reasonably happy lot. In his superb new book *The Boundless Deep* Richard Holmes shows that this was not the case. Using Alfred Tennyson as his fulcrum Holmes unpacks the many intellectual currents that began to completely unhinge Victorian optimism and the Whig interpretation of history as one of linear progress. *The Boundless Deep* has received rave reviews but it isn’t an entirely new idea.…