One of these new political ideas was liberalism. Liberalism owed much to the Enlightenment of the eighteenth century and the American and French Revolutions that erupted at the end of that century. It became increasingly important as the Industrial Revolution progressed because the emerging middle class largely adopted the idea as its own. Opinions diverged among people classified as liberals, but all began with a common denominator, a conviction that in both economic and political terms, people should be as free from restraint as possible. Economic liberalism, also known as classical economics, was based on the tenet of laissez-faire—the belief that the state should not interfere in the free play of natural economic forces, especially supply and demand. Political liberalism was based on the concept of a constitutional monarchy or constitutional state, with limits on the powers of government and a written charter to protect the basic civil rights of the people. Nineteenth-century liberals, however, were not democrats in the modern sense. Although they held that people were entitled to equal civil rights, the right to vote and to hold office would be open only to men who met certain property qualifications. Nationalism was an even more powerful ideology for change in the nineteenth century. The idea arose out of an awareness of being part of a community that had common institutions, traditions, language, and customs. In some cases, that sense of identity was based on shared ethnic or linguistic characteristics. In others, it was a consequence of a common commitment to a particular religion or culture. Such a community came to be called a “nation,” and the primary political loyalty of individuals would be to the nation rather than to a dynasty or a citystate or some other political unit. Nationalism did not become a popular force for change until the French Revolution, when the concept arose that governments should coincide with nationalities. Thus a divided people such as the Germans wanted national unity in a German nation-state with one central government. Subject peoples, such as the Hungarians, wanted national selfdetermination, or the right to establish their own autonomy rather than be subject to a German minority in a multinational empire. Liberalism and nationalism began to exert a measurable impact on the European political scene in the 1830s, when a revolt led by progressive forces installed a constitutional monarchy in France, and nationalist uprisings, often given active support by liberal forces, took place in Belgium (which was then attached to the Dutch Republic), in Italy, and in Poland (then part of the Russian Empire). Only the Belgians were successful, as Russian forces crushed the Poles’ attempt to liberate themselves from foreign domination, while Austrian troops intervened in Italy to uphold reactionary governments in a number of Italian states. In the spring of 1848, a new series of uprisings against established authority broke out in several countries in central and western Europe. The most effective was in France, where an uprising centered in Paris overthrew the so-called bourgeois monarchy of King Louis Philippe and briefly brought to power a new republic composed of an alliance of workers, intellectuals, and progressive representatives of the urban middle class.