The name of the lady was designedly kept in secrecy, and was unknown, except to _a very few_, till some years after d'Holbach's death. We now know from the _Feuilles Posthumes_ of Lequinio, who had it from Naigeon, that the _Letters_ were written several years before their publication, for the instruction of a lady formerly distinguished at the French Court for her graces and virtues. They were addressed to the charming Marguerite, Marchioness de Vermandois. Her husband held the lucrative post of farmer-general to the king, and besides inherited large estates. He possessed excellent natural abilities, and his mind was strengthened and adorned by culture and letters. Had his modesty permitted him, to appear as such, he would now be known as a poet of genius and merit, for he wrote some poems and plays that were much admired by all who were allowed to peruse them. He was married in 1763, on the day he completed his twenty-first year, to Marguerite Justine d'Estrades, then only nineteen years of age, and whom he saw for the first time in his life only six weeks before they became husband and wife. Like most of the matches then made among the higher classes in France, this was one of a purely mercenary character. The father of the Marquis de Vermandois, and the father of Marguerite, as a means of joining their estates, contracted their children without deigning to consult the wishes of the parties, and obedience or disinheritance was the only alternative. When the compact was concluded, Marguerite was taken from the convent where for five years she had lived as a boarder and scholar, and commenced her married life and her course in the fashionable world at the same time. The match was far more fortunate than such matches then generally proved to be. Marguerite's husband was passionately attached to her, and that attachment was returned. The Marquis was a friend of Baron d'Holbach, and soon after his marriage introduced his wife to him. Among all the beauties of Paris the Marchioness was one of the most lovely and fascinating. Her features were remarkably beautiful, and the bloom and clearness of her complexion were such as absolutely to render necessary the old comparison of the rose and the lily to do them justice. To these were added a voluptuous figure, agreeable manners, the graces and vivacity of wit, and the still more enduring attractions of good humor, purity, and benevolence! A female like her could not but be dear to all who enjoyed her intimacy, and a strong friendship sprang up between her and Baron d'Holbach. Greatly pleased with him at first, Marguerite was afterwards as greatly shocked. When their intercourse had become so familiar as to permit that frankness and freedom of conversation which prevails among intimate friends, she discovered that the Baron was an unbeliever in the Christian dogmas which she had learned at the convent, where, in consequence of her mother's death, she had been educated. She