In this sense, the theory of the Communists may be summed up in the single sentence: Abolition of private property. - Manifesto of the Communist Party
Karl MarxWe know only a single science, the science of history. History can be contemplated from two sides, it can be divided into the history of nature and the history of mankind. However, the two sides are not to be divided off; as long as men exist the history of nature and the history of men are mutually conditioned.
Karl Marx