She was born in Paris in 1725, and in 1746 was married to the Comte de Boufflers-Rouvrel; soon after, becoming enamored of the Prince de Conti, she became his acknowledged mistress. To give an idea of the light in which the women of that time considered those who were mistresses of great men, the following episodes may be cited: One day, Mme. de Boufflers, momentarily forgetting her relations to the Prince de Conti, remarked that she scorned a woman who avait un prince du sang (was mistress of a prince of the blood). When reminded of her apparent inconsistency, she said: "I wish to give by my words to virtue what I take away from it by my actions...." On another occasion, she reproached the Maréchale de Mirepoix for going to see Mme. de Pompadour, and in the heat of argument said: "Why, she is nothing but the first fille (mistress) of the kingdom!" The maréchale replied: "Do not force me to count even unto three" (Mme. de Pompadour, Mlle. Marquise, Mme. de Boufflers). In those days, the position of mistress of an important man attracted little more attention than might a petty, trivial, light-hearted flirtation nowadays.
After the death of M. de Boufflers, in 1764, the all-absorbing question of society, and one of vital importance to madame, was, Will the prince marry her? If not, will she continue to be his mistress? In this critical period, Hume showed his friendship and true sympathy by giving Mme. de Boufflers most persuasive and practical advice in reference to morals—which she did not follow. Her relations with Rousseau showed her capable of the deepest and most profound friendship and sympathy. According to Sainte-Beuve, it was she who, by aid of her friends in England, procured asylum for him with Hume at Wootton. When Rousseau's rashness brought on the quarrel which set in commotion and agitated the intellectual circles of both continents, Mme. de Boufflers took his part and remained faithful to him, securing a place for him in the Château de Trie, which belonged to the Prince de Conti.
All who came in contact with her recognized the distinction, elevation of esprit, and sentiment of Mme. de Boufflers. With her are associated the greatest names of the time; being perfectly at home on all the political questions of the day, she was better able to converse upon these subjects than was any other woman of the time. When in 1762 she visited England, she was lionized everywhere. She was fêted at court and in the city, and all conversation was upon the one subject, that of her presence, which was one of the important events of London life. Everyone was anxious to see the famous woman, the first of rank to visit England in two hundred years. She even received some special attention from the eccentric Samuel Johnson, in this manner: "Horace Walpole had taken the countess to call on Johnson. After the conventional time of a formal call had expired, they left, and were halfway down stairs, when it dawned upon Johnson that it was his duty, as host, to pay the honors of his literary residence to a foreign lady of quality; to show himself gallant, he jumped down from the top of the stairway, and, all agitation, seized the hand of the countess and conducted her to her carriage."
No woman at court had more friends and fewer enemies than did Mme. de Boufflers, because "she united to the gifts of nature and the culture of esprit an amiable simplicity, charming graces, a goodness, kindness, and sensibility, which made her forget herself always and constantly seek to aid those about her." She made use of her influence over the prince in such ways as would, in a measure, recompense for her fault, and thus recommended herself by her good actions. She was the soul of his salon, "Le Temple." The love of these two people, through its intimacy and public display, through its constancy, happiness, and decency, dissipated all scandal. Always cheerful and pleased to amuse, knowing how to pay attention to all, always rewarding the bright remarks of others with a smile, which all sought as a mark of approbation, no one ever wished her any ill fortune.
The last days of the Prince de Conti were cheered by the presence of Mme. de Boufflers and the friends whom she gathered about him to help bear his illness. The letter to her from Hume, on his deathbed, is most pathetic, showing the influence of this woman and the nature of the impression she left upon her friends:
"Edinburgh, 20th of August, 1776.
"Although I am certainly within a few weeks, dear Madame, and perhaps within a few days, of my own death, I could not forbear being struck with the death of the Prince of Conti—so great a loss in every particular. My reflection carried me immediately to your situation in this melancholy incident. What a difference to you in your whole plan of life! Pray write me some particulars, but in such terms that you need not care, in case of my decease, into whose hands your letter may fall.... My distemper is a diarrhœa or disorder in my bowels, which has been gradually undermining me for these two years, but within these six months has been visibly hastening me to my end. I see death approach gradually, without any anxiety or regret. I salute you with great affection and regard, for the last time.
"David Hume."
Hume died five days after this letter was written.
The last years of her life she spent with her daughter-in-law, at Auteuil, where she lived a happy life and received the best society of Paris. When she died or under what circumstances is not known. During the Revolution she lived in obscurity, busying herself with charitable work; she was one of the few women of the nobility to escape the guillotine, "This woman, who had kept the intellectual world alive with her esprit and goodness, of a sudden vanishes like a star from the horizon; she lives on, unnoticed by everyone, and, in that new society, no one misses her or regrets her death."