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.