After her marriage to the Marechal de Luxembourg, she decided, about 1750, to open a salon in Paris; it became one of the real forces of the eighteenth century, socially and politically.  While her husband lived, she did not enjoy the freedom she desired; after his death in 1764 she was at liberty to do as she pleased, and she then began her career as a judge and counsellor in all social matters.  She was regarded as the oracle of taste and urbanity, exercised a supervision over the tone and usage of society, was the censor of la bonne compagnie during the happy years of Louis XVI.  This power in her was universally recognized.  She tempered the Anglomania of the time, all excesses of familiarity and rudeness; she never uttered a bad expression, a coarse laugh or a tutoiement (thee and thou).  The slightest affectation in tone or gesture was detected and judged by her.  She preserved the good tone of society and permitted no contamination.  She retarded the reign of clubs, retained the urbanity of French society, and preserved a proper and unique character in the ancien salon francais, in the way of excellence of tone.

The Marquise de Rambouillet, Mme. de La Fayette, Mme. de Maintenon, Mme. de Caylus, and Mme. de Luxembourg are of the same type—­the same world, with little variance and no decadence; in some respects, the last may be said to have approached nearest to perfection.  “In her, the turn of critical and caustic severity was exempt from rigidity and was accompanied by every charm and pleasingness in her person.  She often judged [a person] by [his] ability at repartee, which she tested by embarrassing questions across the table, judging [the person] by the reply.  She herself was never at a loss for an answer:  when shown two portraits—­one of Moliere and one of La Fontaine—­and asked which was the greater, she answered:  ‘That one,’ pointing to La Fontaine, ‘is more perfect in a genre less perfect.’”

By the Goncourt brothers, her salon has been given its merited credit:  “The most elegant salon was that of the Marechale de Luxembourg, one of the most original women of the time.  She showed an originality in her judgments, she was authority in usage, a genius in taste.  About her were pleasure, interest, novelty, letters; here was formed the true elegance of the eighteenth century—­a society that held sway over Europe until 1789.  Here was formed the greatest institution of the time, the only one that survived till the Revolution, that preserved—­in the discredit of all moral laws—­the authority of one law, la parfaite bonne compagnie, whose aim was a social one—­to distinguish itself from bad company, vulgar and provincial society, by the perfection of the means of pleasing, by the delicacy of friendship, by the art of considerations, complaisances, of savoir vivre, by all possible researches and refinements of esprit.  It fixed everything—­usages,