It was not till after her death that he found out for certain that less than two years after she came to him she had given herself, body and soul, to the young Marquis de Mora. But what he did not know, he must have greatly suspected. It was he who wrote her letters and ran her errands. Grimm recorded in the ‘Literary Correspondence’ the prodigious ascendency she had acquired over all his thoughts and actions. ‘No luckless Savoyard of Paris ... does so many wearisome commissions as the first geometrician of Europe, the chief of the Encyclopædic sect, the dictator of our Academies, does for Mademoiselle.’ He would post her fervent outpourings to the man who had supplanted him, and call for the replies at the post-office that she might receive them an hour or two earlier. What wonder that over such a character, a nature like Mademoiselle’s rode roughshod, that she hurt and bruised him a hundred times a day, and wounded while she despised him? No woman ever truly loves a man who does not exact from her not only complete fidelity to himself, but fidelity to all that is best and highest in her own nature. D’Alembert had indeed in full measure the virtue of his defects. If it was a crime to be tender to her sins, it was nobility to be gentle to her sufferings. He bore and forbore with her endlessly. Always patient and good-humoured, thinking greatly of her and little of himself, abundant in compassion for her ruined nerves and the querulous feverishness of her ill health--here surely were some of the noble traits of a good love. He read to her, watched by her, tended her, and in the matchless society they gathered round them was abundantly content to be nothing, that she might be all. Their life together in the Rue Belle Chasse had not in the least shocked their easy-going world. Many persons comfortably maintained that their association was the merest friendship--heedless of that amply proven fact that where people avoid evil, they avoid also the appearance of evil. The eighteenth century, indeed, even if it saw any difference between vice and virtue, which is doubtful, did not in the least mind if its favourites were vicious or virtuous, provided they were not dull. D’Alembert and Mademoiselle de Lespinasse did not fall under that ban. The hermit life the man had led was over for ever. In her modest room in that dingy street, Mademoiselle held every night the most famous _salon_ in Paris.