A well-known example is «Stirps iesse», which is nothing else than a florid organum over a «Benedicamus domino» cantus which was widespread within the Cluniac Monastic Association including the "Magnus liber organi" of the Notre-Dame school. As «Benedicamus domino» verses concluded almost every divine service, Cluniac cantors were supposed to know a great variety of them. Many of them had been new compositions and became favored subjects for new experiments in poetry and musical composition. Florid organum itself like any tropus can be regarded in two ways, as a useful exercise to memorize a certain cantus precisely note by note on the one hand or, as a very refined and embellished performance by a well-skilled soloist or precentor. «Stirps iesse» was actually a combination of both, as a Benedicamus performed «cum organo» it was rather a longer performance during an important liturgical feast, but the troped organal voice added a certain Marian poem to it, which fixed it within the week between Christmas and New Year.