Above all things, Diderot is vehemently in favour of the recognition of literary property, and against such infringement of it as had been ventured upon in the case of La Fontaine.

He had no reason to be especially friendly to booksellers, but for one thing, he saw that to nullify or to tamper with copyright was in effect to prevent an author from having any commodity to sell, and so to do him the most serious injury possible.

And for another thing, Diderot had equity and common sense enough to see that no high-flown nonsense about the dignity of letters and the spiritual power could touch the fact that a book is a piece of marketable ware, and that the men who deal in such wares have as much claim to be protected in their contracts as those who deal in any other wares.[242] There is a vivid illustration of this unexpected business-like quality in Diderot, in a conversation that he once had with D'Alembert.

The dialogue is interesting to those who happen to be curious as to the characters of two famous men.

It was in 1759, when D'Alembert was tired of the Encyclopaedia, and was for making hard terms as the condition of his return to it.