Leoninus [Magister Leoninus; Magister Leonius, Leo, Léonin]
- Edward H. Roesner
( fl Paris, 1150s–c1201). Composer of polyphony , including organum and, probably, conductus. He is credited by the theorist Anonymus 4 with perhaps the single greatest achievement in the development of early polyphony, the creation of the so-called Magnus liber. This collection is believed to constitute the matrix in which polyphony was transformed from performance practice into ‘composition’ in the modern sense of the word. In its repertory appeared a system of consonance and dissonance that would dominate polyphonic composition for the next three centuries, and also a coherent rhythmic language that, for the first time in Western music, expressed itself in its notation. No works are ascribed to Leoninus in musical sources or by contemporaneous theorists....