_The Natural Son_ must, by me at least, be pronounced one of the most vapid performances in dramatic history.

Even Lessing, unwilling as he was to say a word against a writer who had taught him so much, is too good a critic not to recognise monotony in the characters, stiffness and affectation in the dialogue, and a pedantic ring in the sentences of new-fangled philosophy.[251] Even in the three critical dialogues that Diderot added to the play, Lessing cannot help discerning the mixture of superficiality with an almost pompous pretension.

Rosenkranz, it is true, finds the play rich in fine sentences, in scenes full of effect, in which Diderot's moral enthusiasm expresses itself with impetuous eloquence.

But even he admits that the hero's servant is not so far wrong when he cries, "_Il semble que le bon sens se soit enfui de cette maison_," and adds that the whole atmosphere of the piece is sickly with conscious virtue.[252] For ourselves we are ready for once even to sympathise with Palissot, the hack-writer of the reactionary parties, when he says that _The Natural Son_ had neither invention, nor style, nor characters, nor any other single unit of a truly dramatic work.

The reader who seeks to realise the nullity of the _genre serieux_ in Diderot's hands, should turn from _The Natural Son_ to Goldoni's play of _The True Friend_, from which Diderot borrowed the structure of his play, following it as narrowly as possible to the end of the third act.
Seldom has transfusion turned a sparkling draught into anything so flat and vapid.