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.
Most of the salons may be exhaustively described as having been nourished on a little eau sucré and a great deal of wit. But to this one wit alone was light, food, and air. Mademoiselle did not require to give dinners like Madame Necker, or suppers like Madame du Deffand; neither for the beauty which, later, was to make men forgive the mental limitations of Madame Récamier, had she need or use. Tall, pale, and slender, with her infinite, unconscious tact, her mental grace, and her divine sympathy, her passage through the social life of her age has left the subtle perfume of some delicate flower. To be her friend was to feel complete, understood, satisfied. To her, as to a sister of consolation, came Condorcet, marquis, mathematician, philosopher; Saint-Pierre, the pupil of Rousseau and the creator of ‘Paul and Virginia;’ La Harpe, whom she was to help to the Academy; Hénault, whom she had charmed from Madame du Deffand; Turgot, Chastellux, Marmontel. And quietly effacing himself, with that true greatness which is never afraid to be made of little account, was Mademoiselle’s lover and the noblest intellect of them all, d’Alembert.
There is no more delightful trait in his character than this exquisite talent for modesty. With his spare form always dressed from head to foot in clothes of one colour, the aim of d’Alembert was both physically and mentally, as it were, to escape notice. True, when he talked, the listener must needs marvel at the breadth, the variety, the exhaustless interests of the mind, and its perfect simplicity and straightforwardness. But he did not want to talk much. He liked better to listen. He preferred in society, as he preferred in life, to think while other men said and did.
No social pleasures could either supersede the work of his life, or make compensation for the sorrows of his soul. He had already thrown in his lot with Mademoiselle when he published the most daring of all his books, ‘The History of the Destruction of the Jesuits.’ Her treachery had shattered his life for five years, when he asked Frederick the Great for a sum of money which would enable him to travel and heal his broken health and heart. In 1770, with young Condorcet for his companion, he left Paris for Italy, stopped at Ferney, and spent his whole leave of absence with Voltaire.
It was an oasis in the desert of the feverish existence to which he had condemned himself. In mighty speculation, in splendid visions of the future of the race, in passionate argument on the immortality of the soul and the being and nature of God, he forgot his personal sorrows. The mind dominated and the heart was still. What nights the three must have spent together—Voltaire with his octogenarian’s intellect as keen and bright as a boy’s, the young Marquis, sharp-set to learn, and d’Alembert with his ‘just mind and inexhaustible imagination’—when they could get rid of that babbling inconsequence, Voltaire’s niece, Madame Denis, and sit hour after hour discussing, planning, dreaming! The quiet d’Alembert went, as quiet people often do, far beyond his impulsive and outspoken companions in speculative daring. Though there is not an anti-Christian line in any of his published writings except his correspondence, yet the scepticism of this gentle mathematician far exceeded that of him who is accounted the Prince of Unbelievers, and where his host was a hotly convinced Deist, d’Alembert only thought the probabilities in favour of Theism, and was far more Voltairian than Voltaire. It was the old Pontiff of the Church of Anti-Christ who stopped a conversation at his table wherein d’Alembert had spoken of the very existence of God as a moot point, by sending the servants out of the room, and then turning to his guests with—‘And now, gentlemen, continue your attack upon God. But as I do not want to be murdered or robbed to-night by my servants, they had better not hear you.’
The visit lasted in all two months. D’Alembert abandoned the Italian journey, offered King Frederick his change, and returned to Paris.
In 1772 he was made Perpetual Secretary of the French Academy. He, whose needs, said Grimm, were always the measure of his ambitions, had scaled heights, not beyond his deserts, but beyond his wishes. He was also a member of the scientific Academies of Prussia, Russia, Portugal, Naples, Turin, Norway, Padua, and of the literary academies of Sweden and Bologna. But if ‘the end of all ambition is to be happy at home,’ d’Alembert had failed. When the Perpetual Secretaryship was still a new and dazzling possession, the Perpetual Secretary found at home the woman to whom he was captive soul and body, in the throes of another passion. False to de Mora, as she had been false to him, she was then writing to de Guibert those love-letters which have given her a place beside Sappho and Eloïsa and have added a classic to literature. It was d’Alembert’s part to listen to self-reproaches whose justice he might well guess, to look into the depths of a tenderness in which he had no share. Once he gave her his portrait with these lines beneath it:
Et dites quelquefois en voyant cette image
De tous ceux que j’aimai, qui m’aima comme lui?
She herself said that of all the feelings she had inspired, his alone had not brought her wretchedness.
In 1775 de Guibert was married. The marriage was Mademoiselle’s death-blow. The fever of the soul became a disease of the body. Sometimes bitterly repentant and sometimes only captious and difficult; now, her true self full of tenderness and charm: and now, reckless, selfish, despairing—d’Alembert’s patience and goodness were inexhaustible. True to his character, he stood aside that to the last her friends might visit her, that to the last she might help and feel for them.