This article treats the hyperinfl ation (1791-1797), « which eviscerated most families’ patrimony, and a remedy, as unexpected as it was controversial, the l’action en rescision pour lésion d’outre-moitié ». While the assignat fell to less than one per cent of its nominal value, terrifi ed families sold off shops, homes and farms to survive the crisis. Often, these properties were sold for less than half their value, causing lawyers to revive these suits with their roots in Roman law. The law allowed sellers to sue buyers for more money to « repair » the inadequate amount in the sales contract. The fi ery debates of the legislators shook French society and threw many thousands of sales into question. The law of 19 fl oréal VI reopened these suits and sellers seized on the possibilities that this legislation offered them. The 531 suits found in the archives of the Yvelines department attest to the ferocity with which sellers pursued their buyers. Far beyond these legal proceedings, this form of civil suit lay at the crossroads of discussions that animated the world of eighteenth-century jurists and that targeted key elements of any legitimate contract: Was itthe « meeting of minds » or equity that rendered a contract legitimate?These suits, then, illuminate not only the shocking upheaval of the hyperinflation, but also the polemics that accompanied the development of themodern contract.