This work was written by K. Marx in French as a reply to the book by the French politician and sociologist P.-J. Proudhon, “The System of Economic Contradictions, or The Philosophy of Poverty.” In his “Poverty of Philosophy,” the author—through criticism of Proudhon—first laid out for the general public the starting points of his economic doctrine, offering what, twenty years later, became a coherent theory developed in “Capital.” This edition includes two letters by K. Marx as well, which also contain criticism of Proudhon’s views.