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. But though the spirit still triumphed at moments over the body, the end was near. When her misery was dulled by opium, d’Alembert was always watching, unheeded, at her bedside. It was the attitude of his life. When she became conscious, he was there still. Before she died, she asked his pardon; but de Guibert’s was the last name upon her lips. She died on May 23, 1776, not yet forty-five years old. D’Alembert’s grief seems to have taken by surprise many short-sighted friends who had supposed that quiet exterior to hide a cold, or an unawakened, heart. He was utterly crushed and broken. His life had lost at once its inspiration and its meaning. For the sake of Mademoiselle he had grown old without family and without hope. His friends, in that age of noble friendships, did their best to comfort him. But his wounds were deeper than they knew. With a super-refinement of selfishness or cruelty, Mademoiselle had left him her Correspondence. She had not preserved in it one single line of the many letters he had himself written to her, while it contained full and certain proofs of her double infidelity. He who has lost only those of whose faith and truth he is sure, has not yet reached the depth of human desolation. After a while, d’Alembert tried to return to his first affection--that cold but faithful mistress, his mathematical studies. At the Academy he pronounced the _éloge_ of Louis de Sacy, who had been the lover of the Marquise de Lambert. For the first time he looked into his heart and wrote, and thus for the first time he touched the hearts of others; the cold style took fire, and beneath the clumsy periods welled tears.