Definition
A 'cantus firmus' is a pre-existing melody used as the foundation for a polyphonic composition. Think of it like the sample in a rap song, but from centuries ago. 🎵 It's usually a well-known tune, often a plainchant melody. Composers weave new melodic lines around it, creating complex harmonies. It's like building a musical skyscraper on a solid foundation. Unlike a solo piece, the 'cantus firmus' supports and interacts with other melodies.