By the Goncourt brothers, her salon has been given its merited credit: "The most elegant salon was that of the Maréchale 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, etiquette, tone of conversation; it taught how to praise without bombast and insipidness, to reply to a compliment without disdaining or accepting it, to bring others to value without appearing to protect them; it prevented all slander. If it did not impart modesty, goodness, indulgence, nobleness of sentiment, it at least imposed the forms, exacting the appearances and showing the images of them. It was the guardian of urbanity and maintained all the laws that are derived from taste. It represented the religion of honor; it judged, and when it condemned a man he was socially-ruined." A type of what may be called the social mistress of the nobility--the personification of good taste, elegance and propriety such as it should be--was the Comtesse de Boufflers, mistress of the Prince de Conti, intimate friend of Hume, Rousseau, and Gustave III., King of Sweden. The countess was one of the most influential and spirituelle members of French society, her special mission and delight being the introduction of foreign celebrities into French society. She piloted them, was their patroness, spoke almost all modern languages, and visited her friends in their respective countries. She was the most travelled and most hospitable of great French women, hence the woman best informed upon the world in general.