The greatest body of compositions by this artist known today was created thanks to the interest that the legacy of the Roman Catholic bishop had for musicians working for the Lutheran church of St Mary Magdalene in Wrocław. They made, mainly in the 1850s, copies of more than 30 works by Mielczewski, signing them in their manuscripts with the initials ‘M.M.’

Compositions of the ‘M.M.’ along with the entire collection of musicalia from the church of St Mary Magdalene, as well as from other Wrocław churches, were stored in the 19th century in the local City Library. They were catalogued and subjected to research by musicologists from Germany and other European countries, but their author was not identified. From 1945, for almost 50 years, the entire collection of musical manuscripts from the 16th and 17th centuries belonging to Wrocław City Library was considered missing. We now know that it was taken to Moscow after World War II, and then, in the 1950s, transferred to the German Democratic Republic and deposited at the Staatsbibliothek Preußischer Kulturbesitz in former East Berlin, where it was not accessible until the fall of the Berlin Wall. It was not until the 1990s that it was possible to continue research on the successfully recovered valuable Silesian manuscripts. They allowed us to attribute the authorship of the ‘M.M.’ included in this collection to Marcin Mielczewski.”