“Pope’s Essay on Man,” wrote Voltaire after his return from England (1728), “seems to me the finest didactic poem, the most useful, the most sublime, that was ever written in any tongue.  ’Tis true the whole substance of it is to be found in Shaftesbury’s Characteristics, and I do not know why Pope gives all the honour of it to Bolingbroke, without saying a word of the celebrated Shaftesbury, the pupil of Locke."[40] The ground of this enthusiastic appreciation of the English naturalism was not merely that it made morality independent of religion, which Shaftesbury took great pains to do.  It also identified religion with all that is beautiful and harmonious in the universal scheme.  It surrounded the new faith with a pure and lofty poetry, that enabled it to confront the old on more than equal terms of dignity and elevation.  Shaftesbury, and Diderot after him, ennobled human nature by placing the principle of virtue, the sense of goodness, within the breast of man.  Diderot held to this idea throughout, as we shall see.  That he did so explains a kind of phraseology about virtue and morality in his letters to Madame Voland and elsewhere, which would otherwise sound disagreeably like cant.  Finally, Shaftesbury’s peculiar attribution of beauty to morality, his reference of ethical matters to a kind of taste, the tolerably equal importance attributed by him to a sense of beauty and to the moral sense, all impressed Diderot with a mark that was not effaced.  In the text of the Inquiry the author pronounces it a childish affectation in the eyes of any man who weighs things maturely to deny that there is in moral beings, just as in corporeal objects, a true and essential beauty, a real sublime.  The eagerness with which Diderot seized on this idea from the first, is shown in the declamatory foot-note which he here appends to his original.[41] It was the source, by a process of inverted application, of that ethical colouring in his criticisms on art which made them so new and so interesting, because it carried aesthetic beyond technicalities, and associated it with the real impulses and circumstances of human life.[42]

One of Diderot’s writings composed about our present date (1747), the Promenade du Sceptique, did not see the light until after his death.  His daughter tells us that a police agent came one day to the house, and proceeded to search the author’s room.  He found a manuscript, said, “Good, that is what I am looking for,” thrust it into his pocket, and went away.  Diderot did his best to recover his piece, but never succeeded.[43] A copy of it came into the hands of Naigeon, and it seems to have been retained by Malesherbes, the director of the press, out of goodwill to the author.  If it had been printed, it would certainly have cost him a sojourn in Vincennes.