The correspondence between Paul Hindemith and the publishing house B. Schott's Söhne in Mainz comprises around 2800 documents. The protagonists are, on the one hand, Paul Hindemith and his wife Gertrud who, as a competent confidant, continued the business with the publishing house even after the death of her husband, and, on the other hand, the then owners of the publishing house, Ludwig and Willy Strecker, and some of their employees. Over a period from 1919 to 1967, the correspondence not only paints a vivid picture of Hindemith's relationship with his publishers, which developed into friendship over the decades, but also provides exclusive insights into the artistic developments and political upheavals of modernism - an extraordinary document of 20th-century music history.