The new species known as _comédie larmoyante_ was now fairly in the ascendant; and it would be easy to show how even Voltaire, who had deprecated the innovation, had to yield to a power greater than his own, and introduced the sentimental element into some of his comedies.[132] The further step, by which _comédie larmoyante_ was transformed into _tragédie bourgeoise_, from which the comic element was to all intents and purposes extruded, was taken by a great French writer, D. Diderot; to whose influence it was largely due that the species which had attained to this consummation for more than a generation ruled supreme in the dramatic literature of Europe. But the final impulse, as Diderot himself virtually acknowledged in the _entretiens_ subjoined by him to his _Fils naturel_ (1757), had been given by a far humbler citizen of the world of letters, the author of _The London Merchant_. Diderot's own plays were a literary rather than a theatrical success. _Le Fils naturel ou les épreuves de la vertu_ was not publicly performed till 1771, and then only in deference to the determination of a single actor of the Français (Molé); nor was the performance of it repeated. Diderot's second play, _Le Père de famille_, printed in 1758 with a _Discours sur la poésie dramatique_, went through a few public performances in 1761; and a later revival was unsuccessful. But "at a distance," as was well said, the effect of Diderot's endeavours, the earlier in particular, was extremely great, and Lessing, though very critical as to particular points, greatly helped to spread it. Diderot had for the first time consciously sought to proclaim the theatre an agency of social reform, and to entrust to it as its task the propagation of the gospel of philanthropy. Though the execution of his dramatic works fell far short of his aims; though Madame de Staël was not far wrong in denouncing them as exhibiting not nature itself, but "the affectation of nature," yet they contained, in a measure almost unequalled in the history of the modern drama, the fermenting element which never seems to subside. Their author announced them as examples of a third dramatic form--the _genre sérieux_--which he declared to be the consummation of the dramatic art. Making war upon the frigid artificiality of classical tragedy, he banished verse from the new species. The effect of these plays was intended to spring from their truth to nature--a truth such as no spectator could mistake, and which should bring home its moral teachings to the business as well as the bosoms of all. The theatre was to become a real and realistic school of the principles of society and of the conduct of life--it was, in other words, to usurp functions with which it has no concern, and to essay the direct reformation of mankind. The idea was neither new nor just; but its speciousness will probably continue to commend it to many enthusiastic minds, whensoever and in whatsoever shape it is revived.