"I consider him a genius," remarked Arnold Schoenberg of the progressive early modernist Max Reger (1873–1916). In addition to his international renown as a teacher, conductor, and pianist, Reger wrote more than 1,000 works in virtually every musical genre. Many scholars and musicians credit him with emancipating dissonance to a level that assisted Schoenberg's development of serialism in the 1920s. Reger's influence extends to other 20th-century composers, including Béla Bártok, Alban Berg, Arthur Honegger, Paul Hindemith, and Sergei Prokofiev. Modulation — the change from one key to another — is a subject of critical importance to performers and composers in their study of harmony. Reger wrote this concise guide to modulation while teaching composition at Leipzig Conservatory, and the work continues to provide valuable insights and instruction for musicians at all levels. This new edition features newly engraved musical examples.