Cabinet noir (French for "black room") was the name given in France to the office where the letters of suspected persons were opened and read by public officials before being forwarded to their destination. However, this had to be done with some sophistication, as it was considered undesirable that the subjects of the practice know about it, and "that the black chamber not interrupt the smooth running of the postal service." This practice had been in vogue since the establishment of posts, and was frequently used by the ministers of Louis XIII and Louis XIV; but it was not until the reign of Louis XV that a separate office for this purpose was created. This was called the cabinet du secret des postes, or more popularly the cabinet noir. Although declaimed against at the time of the French