The monochord is a string instrument that became known through the experiments of Pythagoras and still plays a central role in harmonic research today. Its triumph into the instrument collections of musicians, music educators, music therapists, and experimental enthusiasts began in the 1980s, after the monochord gained recognition at the Free Music Center Munich in music therapy and harmonic seminars, as well as in construction and playing workshops. Today, due to its ease of play, it helps many people rediscover their own musicality and is naturally used in music therapy, music education, and music productions. The two authors were significantly involved in this process and provide detailed information about the various aspects of the monochord in this book. Beginning with a historical overview, it leads into.