After "La Bête Humaine" in the summer of 1890, Zola turned to "L'Argent," a tale of the Paris financial world, inspired chiefly by the crash of the Union Générale Bank some years before. Of all the subjects he had hitherto approached he found this the most difficult to treat. He had no financiers among his friends, he had never dabbled in Bourse gambling, and was at a loss for information respecting much of the inner working of what the French call _la haute banque_. However, while frequenting the Bourse almost daily for a whole month, he obtained enlightenment from some gentlemen of the stock-broking world, to whom he was introduced. He also studied the detailed reports of the great swindles of previous years, going back as far as the time of the notorious Mirès, which was, of course, legitimate, the period of his story being that of the Second Empire. One may add that in writing his book he did not spare some of the Jew financiers of Paris. "L'Argent" appeared serially in the "Gil Blas," which paid twelve hundred pounds for the privilege, and was issued as a volume in 1891.[14] Goncourt mentions that while Zola was writing the work he again expressed his anxiety to finish his series. There were to be only two more volumes, one on the Franco-German war of 1870, and the other, in which he then took most interest, a general summing-up of his "family history" by a scientific man, Dr. Pascal Rougon, whom he thought of marrying to some retrograde, bigoted woman who would destroy successively everything he wrote. And Zola sighed that he wished he could obtain permission to inspect the papers of Claude Bernard, on whose published writings he had reared, as will be remembered, his theory of _le roman expérimental_. As for his projected "war" book, he did not think he could make much of a novel of it. His idea at that moment was to show some character "promenading" through the siege of Paris and the Commune.[15]