The history of communism encompasses a wide variety of ideologies and political movements sharing the core theoretical values of common ownership of wealth, economic enterprise, and property. Most modern forms of communism are grounded at least nominally in Marxism, a theory and method conceived by Karl Marx during the 19th century. Marxism subsequently gained a widespread following across much of Europe and throughout the late 1800s its militant supporters were instrumental in a number of failed revolutions on that continent. During the same era, there was also a proliferation of communist parties which rejected armed revolution, but embraced the Marxist ideal of collective property and a classless society.