LEONIN,   

The French composer known as Lonin or Magister Leoninus is said to have been active in Paris in the second half of the 12th century, associated with the new church of Notre Dame. His reputed achievement lies in the development and transcription of organa, embellishments of plainchant by the addition of a second voice, preserved in the Magnus Liber, the great book of Notre Dame. This seems to record current practice there in polyphonic performance. The collection was said to have been revised in later years by Protin.