One of the most interesting of all the documentary memorials of the century is to be found in the letters which Diderot wrote to Mademoiselle Voland. No doubt has ever been thrown on the authenticity of these letters, and they bear ample evidence of genuineness, so far as the substance of them is concerned, in their characteristic style. They were first published in 1830, from manuscripts sold to the bookseller the year before by a certain French man of letters, Jeudy-Dugour by name. He became a naturalised Russian, changed his name to Gouroff, and died in the position of councillor of state and director of the university of St. Petersburg. How he came by any papers of Diderot it is impossible to guess. It is assumed that when Mademoiselle Voland died her family gave his letters and other papers back to Diderot. These, along with other documents, are supposed to have been given by Diderot to Grimm. Thence they went to the Library of the Hermitage at St. Petersburg. Whether Jeudy-Dugour sold copies or originals, and whether he made the copies, if copies they were, from the Library, which was, however, rigorously closed during the reign of Nicholas I., are literary secrets which it is impossible to fathom. So far as Diderot is concerned, some of the spirit of mystification that haunted literature in the eighteenth century still hovers about it in the nineteenth. This we shall presently find in a still more interesting monument of Diderot than even his letters to Mademoiselle Voland.[194] They are not a continuous series. It was only when either Diderot was absent from Paris, or his correspondent was away at her mother's house in the country, that letter-writing was necessary. Diderot appears to have written to her openly and without disguise. The letters of Mademoiselle Voland in reply were for obvious reasons not sent to Diderot's house, but under cover to the office of Damilaville, so well known to the reader of Voltaire's correspondence. Damilaville was a commissioner in one of the revenue departments, and it is one among many instances of the connivance between authority and its foes, that most of the letters and packets of Voltaire, Diderot, and the rest of the group, should have been taken in, sent out, guarded, and franked by the head of a government office. The trouble that Damilaville willingly took in order to serve his friends is another example of what we have already remarked as the singular amiability and affectionate solicitude of those times. "Think of Damilaville's attention," says Diderot on one occasion: "to-day is Sunday, and he was obliged to leave his office. He was sure that I should come this evening, for I never fail when I hope for a letter from you. He left the key with two candles on a table, and between the two candles your little letter, and a pleasant note of his own." And by the light of the candles Diderot at once wrote a long answer.[195]