The French scholar Marin Mersenne described the process of getting his Harmonie universelle printed as ‘unbelievably hard work’. Mersenne was obviously annoyed by the costs, and Ballard’s insistence on printing the book himself. The printing privilege of Ballard was ‘a restrictive, monopolistic measure’ ‘to support individual printers’ as Richard Agee describes. Throughout his life, Mersenne acted on behalf of others to get books printed or obtain privileges. Although he was not always successful in the execution of such tasks, he offered many authors help in publishing or dissemination and saw himself as an entremetteur or middleman. When we look at the Harmonie through the lens of music printing, the ways in which he organised his work into smaller treatises, and how his efforts to develop a new notational system gained extra urgency. In the fields of music and music printing, Mersenne acted on behalf of others to obtain privileges or transmit material to the printer.