Cachet, Lettres de, in France, were so called in contrast to letters patent (which were open), and were sealed letters signed by the king and countersigned by a secretary of state. They were expressions of the personal will of the sovereign, and for the last two centuries before the revolution were employed (a) to direct certain political bodies to discuss particular subjects, (b) to send persons to exile or prison, which could be done by a simple expression of the royal will without trial. It is this latter use of them which is best known. They were freely used after the edict of Nantes to break up Protestant families and so make proselytes, while at some periods they could easily be obtained signed in blank, and so were often used to gratify private ends. The system was violently condemned by Voltaire, and was finally abolished during the Revolution by a law of January 15, 1790.