One of the most remarkable periods of idealism for both Unitarianism and Universalism arose during the 1800s. Spurred by the mechanical and industrial revolutions, the 19th-century was a time of great fermentation of new ideas. On the scientific front, the century saw the development of general anesthesia, advances in the understanding of genetics, and the 1859 publication of Charles Darwin's theory of evolution in On The Origin of the Species. The world was immeasurably broadened by advances in transportation and communication with the invention of the telegraph, the telephone, and the gasoline-powered automobile. While the Suez (completed in 1869) and Panama Canals facilitated transport by water, railroads were replacing ships as the primary means of transporting goods.
Just as in science and industry, the social order was undergoing a revolution. In the arts, a new Romanticism grew in response to the rationalism of the Age of Enlightenment and a social order of aristocratic imperialism. Philosophers brought revolutionary new ideas about the nature of human beings, and of morality. Indeed it was a time of revolution as freedom and egalitarianism stood as new ideals against monarchy and a social order of privilege and obedience. Revolutions for independence from foreign or monarchic rule arose in many places around the globe including the 1848 revolutions and revolts in Italy, France, Germany, Denmark, Hungary, Belgium, Ireland and Brazil. Although the Russian Revolution was not to come until the 20th century, publication of The Communist Manifesto in 1848 introduced the political philosophy of Karl Marx.
In the United States, the success of the American Revolution ushered in a time of expansion, optimism, and enthusiasm for the new ideals of freedom and egalitarianism. The boundaries of the new nation were still being set with Canada and Mexico, and the potential of the United States was seen as unlimited.
Yet, the first part of the 19th century saw a dramatic increase in the African slave trade as people were captured and brought in bondage to serve the demands of an expanding United States economy. Like all periods of human history, the 19th century embodied contradictions. Prosperity and idealism were the call of the day, but the new order was not without cost or problems. The Mexican-American War (1846-1848) and the American Civil War (1860-1865) were just two conflicts that scarred the continent, while the Napoleonic Wars, the Crimean War, the Opium Wars, the Boer Wars and the Barbary Wars scarred the world. Indigenous peoples were swept aside or exploited by European and American imperialism and expansionism. Arguably, working class people and the indigent in the U.S. neither benefitted from, nor enjoyed discussion about, the century's optimism; some voices were raised against economic expansion they saw characterized by greed and dehumanization. It was a time characterized by sweeping shifts of revolution and counter-revolution, expansion and withdrawal, and the breaking apart of one world order and the establishment of a new one.