Nationalism can take a number of forms, varying over time and place. The emergence of modern nationalism in post French Revolution Europe was characterized by an identification with people who shared a common cultural and linguistic heritage. Often these identifications transcended the borders of European kingdoms and empires, and nineteenth-century nationalism in many countries took the form of attempting to create political bodies that corresponded with nationalist identities. Many of these nationalisms were fictive, seldom corresponding to rhetoric, and one prominent historian of nationalism, Benedict Anderson, has famously observed that modern nationalism emerged with the advent of "print capitalism," which enabled people to create what he called "imagined communities." Nationalism as it has been imagined in many countries, including the United States, has often been characterized by a spirit of exclusion as much as inclusion, as people defined themselves against other ethnic groups or proscribed others that were less "American" due to different languages or religions or political views (like communism) that were outside the mainstream. It should be noted, however, that at least initially, nationalism in Europe often accompanied liberal ideas such as representative government, befitting a movement that rose in opposition to dynastic empires. Over time, however, nationalism became conflated with emerging pseudosciences of race, and took on the more poisonous character represented by totalitarian movements of the twentieth century. But also in the twentieth century, leaders such as Martin Luther King and Gandhi made explicit and nonracial appeals to nationalism in their freedom movements. So nationalism has meant different things at different times.