The Poverty of Philosophy (Barnes & Noble Digital Library)

Marx wrote this 1847 work in response to Pierre-Joseph Proudhon's 1847 book, The System of Economic Contradictions, or Philosophy of Poverty.  Accusing Proudhon of not only wanting to rise above the bourgeoisie, but also adhering to a quasi-religious faith in economic utopianism; Marx, on the contrary, proposes a scientific approach to the study of economic development.