The studies of Cardine and his students ( Godehard Joppich, Luigi Augustoni, Johannes B . G�schl, Marie-No�l Colette, Rupert Fischer, Marie-Claire Billecocq, Alexander M . Schweitzer to name a few ) have clearly demonstrated that rhythm in Gregorian chant as notated in the 10th century rhythmic manuscripts ( notably Skt.
32.
A considerable number of well-known hymns ( e . g . " Ave Maris Stella ", " A Solis Ortus Cardine ", " Jesu Redemptor Omnium, " " Iste Confessor " ) are not in the Ambrosian Hymnal, but there are many there which are not in the Roman, and those that are common to both generally appear as they were before the revisions of Urban VIII, though some have variants of their own.
33.
Inspired by, and based on, some of the ideas / concepts of the eminent 20th-century philosopher Jacques Derrida, it aimed to challenge the premises of the comparative methodologies employed by Dom Eug�ne Cardine and his semiological school to study the meaning of the chant signs, as well as to challenge other very influential Gregorian chant theories that are based on the notion of formula and on concepts that are closely related to it such as that of variant, identity, the oral and the written in chant transmission, and the concept of sign meaning.
