And so a criticism of socialism helps Proudhon to define the positive basis of his own system. The terms of the social problem as it presents itself to him can now be clearly followed. On the one hand there is the suppression of the unearned income derived from property—a revenue which is in direct opposition to the principle of reciprocal service. On the other hand, property itself must be preserved, liberty of work and right of exchange must be secured. In other words, the fundamental attribute of property must be removed without damaging the institution of property itself or endangering the principle of liberty.[652] It is the old problem of how to square the circle. The extinction of unearned incomes must involve the communal ownership of the instruments of production, although Proudhon did not seem to think so. Hitherto the reform of property had been attempted by attacking the production and distribution of wealth. No attention was ever paid to exchange. But Proudhon thought that in the act of exchange inequality creeps in and a new method of exchange is needed. Towards the end of the _Contradictions économiques_ he gives us an obscure hint of the kind of reform to be aimed at. After declaring that nothing now remains to be done except “to sum up all contradictions in one general equation,” he proceeds to ask what particular form that equation is to take. We have already, he remarks, been permitted a glimpse of it. “It must be a law of exchange based upon a theory of mutual help. This theory of mutualism—that is, of natural exchange—is from the collective point of view a synthesis of two ideas—that of property and that of communism.”[653] No further definition is attempted. In a letter written after the publication of the _Contradictions_ he still refers to himself as a simple seeker, and states that he has a new book in preparation, in which these propositions are to be further developed. About the same time he had laid out his plans for active propaganda in the press. But the Revolution of 1848 threw him into the _mêlée_ of party politics and hastened the publication of his theories. In order to give a better idea of the place occupied by Proudhon’s ideas, and to show how they were connected with the socialist experiments of the time, we must say a few words about the Revolution itself. II: THE REVOLUTION OF 1848 AND THE DISCREDIT OF SOCIALISM