This little book of organum (mainly taken from the 13th-century Magnus liber organi) contains all the performing editions used and subsequently revised by TONUS PEREGRINUS on their acclaimed recording of Sacred Music from Notre-Dame Cathedral (Naxos 8.557340): the birth of polyphony from plainchant via simple 9th-century harmonies and the elaborate duets of Master LŽonin (known as organum) to the first music in four independent parts by Master PŽrotin c.1200. The music of Notre-Dame in Paris expanded harmonically and temporally - as the Cathedral itself grew in size and splendour. Ideal for Christmas and all grand feasts.