Louis Dufour de Longuerue (1652, Charleville-Mézières, Ardennes) – 22 November 1733), abbé of Sept-Fontaines (from 1674) and of Saint-Jean-du-Jard near Melun (from 1684), known simply as the abbé de Longuerue, was an antiquarian, a linguist and historian, a child prodigy who became the protégé of Fénelon; in his turn Longuerue encouraged the Abbé Alary and the young cartographer-to-be, Jean Baptiste Bourguignon d'Anville (1697–1782), perhaps the greatest geographical author of the eighteenth century. As a philologist, he remarked on the astonishing progress the French language had made, in its refinement and conscious purification from 1630 to 1670. The abbé was a free-thinker, for a man ostensibly of the cloth: Helvétius quoted[1] his remark that, if all the good and all the evil done in the name of religion were weighed together, the evil would preponderate.[2]
His great work was his Description de France,[3] one of the secondary sources used by Edward Gibbon for his Decline and Fall of the Roman Empire.
Louis was born in Charleville-Mézières, the son of Pierre Dufour, seigneur de Longuevue et Goisel, a Gentilhomme de Normandie and governor of Charleville.[4] His elder brother, who had been expected to succeed to the title and was already a field marshal awarded the Order of St. Louis, was killed at the battle of Ramillies, 1706.
After his death in Paris a volume of Longueruana was published,[5] based on the recollections of a devoted amanuensis who had transcribed Longuerue's savant conversations.[6] In 1769 a further selection of fugitive pieces from among his papers was published.[7]