The musician and composer Paul Natorp has not been recognised in research. The references in his Self-Presentation (Selbstdarstellung) (1921) to the importance of music, especially in his early years, have so far remained unacknowledged. The musical legacy and previously unpublished diaries and letters provide more detailed information. They demonstrate the young Natorp’s passionate relationship with music. In addition, it becomes clear that Natorp was active as a composer throughout his life. The article starts by describing the musical legacy. At the centre is the correspondence with Johannes Brahms, to whom the young Natorp submitted some of his compositions for review. Brahms strongly advised against a career as a musician and composer. Also significant are reports from the young Natorp about his composition studies with the musicologist and composer Gustav Jacobsthal (1845-1912) in Strasbourg. Reports on concerts with Clara Schumann and Franz Liszt are biographical and cultural-historical documents. The article concludes with a sketch of Natorp's reflections on the world-historical significance of Ludwig van Beethoven’s music.