Finally, the essay on Property is important because it led socialists and even political economists to a revision of their theories and a more careful observation of facts. Louis Blanc discouraged fantastical and supernatural schemes of reform; but the sharp, cutting criticism of Proudhon, directed now against the communists, now against the Saint-Simonians and Fourierists, now against the political economists, rendered them impossible. High-priests and revealers of visions could henceforth count on no favor on the part of the laborers. Proudhon disposed of his printing establishment in 1843, but at such a loss as to leave him in debt to the amount of 7000 francs, which, however, he was finally able to pay. His next business enterprise was the formation of a connection with a company which was engaged in transportation on the Saone and the Rhone. This occupation lasted five years, but he did not, in the meantime, cease his literary labors. In 1846 he published his “Système des Contradictions Économiques ou Philosophie de la Misère.”[122] If the work, “Qu’est-ce que la Propriété?” ranks first in importance of all his works, this certainly occupies the second place. It contains a sharp criticism of socialistic and economic theories, which he opposes to one another, and shows that they are mutually destructive. Here, as elsewhere, no one has doubted the merit of his criticism. He adopted as the motto of the book “_Destruam et ædificabo_”—“I will destroy and I will build up again.” He was powerful as a destroyer, but weak as a constructor. He could not keep the second part of his promise. He had become imperfectly acquainted with the Hegelian logic at second-hand through Carl Grün, who became his translator, and he sought to unite contradictories, “thesis” and “antithesis,” into a “synthesis.” But Hegel is not an author whom a Frenchman is likely to understand, and Proudhon did not succeed well in the use of his logical method.