Reading Michael Hardt’s piece in The Idea of Communism, I am reminded of the power of Marx’s argument in the Economic and Philosophic Manuscripts. Here is just a snippet from the Early Writings:
Communism is the positive supersession of private property as human self-estrangement, and hence the true appropriation of the human essence through and for man; it is the complete restoration of man to himself as a social, i.e. human, being, a restoration which has become conscious and which takes place within the entire wealth of previous periods of development.
Path to the Possible 