Pierre-Joseph Proudhon 
What is Property? [PDF ebook] 
An Inquiry Into the Principle of Right and of Government

French printer and pamphleteer Pierre-Joseph Proudhon was an autodidact who became increasingly interested in political philosophy and rose from humble roots to engage in discourse and debate with some of the top thinkers of the day, including Karl Marx. Based in part on the discussion in What is Property?, Proudhon refined the political theory of anarchy and was one of the first known thinkers to call himself an anarchist. A must-read for anyone interested in delving into the roots of capitalism.