Basel's music scene was significantly shaped by the person and work of Paul Sacher, who advocated for both contemporary music and, among other things, founded the Schola Cantorum Basiliensis for early music. New and old music were also the two main themes of the 3rd Basel Congress on Music Theory, the proceedings of which are published in this volume. On one hand, the volume contains contributions that examine the theory, models, and dissemination of 20th-century music. On the other hand, it addresses open questions in the field of early music regarding the counterpoint of the 15th and 16th centuries and considers the relationship between theoretical constructs and compositional practice. Additional contributions specifically analyze the harmony in the late compositions of Franz Schubert.