had been taught that an Infidel was a monster in all respects, and she was astounded to find unbelievers in men so agreeable in manners and person, and so profound in learning, as d'Holbach, Diderot, d'Alembert, and others. She could deny neither their goodness nor their intellectual qualities, and while she admired the individuals she shuddered at their incredulity. Especially did she mourn over Baron d'Holbach. He had a wife as charming as herself, formerly the lovely Mademoiselle d'Aine, whose beautiful features and seductive figure presented "A combination, and a form, indeed, Where every god did seem to set his seal." Nothing was more natural than that two such women should imbibe the deepest tenderness for each other. But alas! the Baron's wife was tainted with her husband's heresies; and yet in their home did the Marchioness see all the domestic virtues exemplified, and beheld that sweet harmony and unchangeable affection for which the d'Holbachs were eminently distinguished among their acquaintances, and which was remarkable from its striking contrast with the courtly and Christian habits of the day. At a loss what to do, the Marchioness consulted her confessor, and was advised to withdraw entirely from the society of the Baron and his wife, unless she was willing to sacrifice all her hopes of heaven, and to plunge headlong down to hell. Her natural good sense and love of her friends struggled with her monastic education and reverence for the priests. The conflict rendered her miserable; and unable to enjoy happiness, she retired to her husband's country seat, where she brooded over her wishes and her terrors. In this state of mind she at length wrote a touching letter to the Baron, and laid open her situation, requesting him to comfort, console, and enlighten her. Such was the origin of the book now presented in an English dress to the reader. It accomplished its purpose with the Marchioness de Vermandois, and afterwards its author concluded to publish the work, in hopes it might be equally useful to others. The Letters were _written_ in 1764, when d'Holbach was in the forty-second year of his age. Twelve different works he had before written and published, and all without the affix of his name. _Eleven_ were upon mineralogy, the arts and the sciences, and _one_ only upon theology. That _one_ had been secretly printed in 1761, at Nancy, with the imprint of London, and was _honored_ with a parliamentary statute condemning its publication and forbidding its sale or circulation. Christian hatred bestowed upon it the additional honor of causing it to be burned in the streets of Paris by the public executioner. But the prudence of the author protected his life. He attributed the book to a dead man, who had been known to entertain sceptical views. It was entitled Christianity Unveiled, and bore on its title page the name of Boulanger. This was d'Holbach's first contribution to Infidel literature, and the second similar work written