and was thereby able to explain for the first time the previously baffling and unprecedented verse structures of many motet texts." Others claim that by the removal of the text of a motet in its original composition, it was changed into a clausula. As the relationship between clausulae and motets is very complicated, there are conflicting conclusions on whether the clausula or the motet came first. Instead, the relationship between the two is complexly intertwined and closely influenced by each other. Function and development Clausulae enriched pre-existing settings of organum. Hundreds of clausulae in two, three and four parts were incorporated into the Magnus Liber Organi of Léonin and Pérotin. Others were arranged in liturgical order within manuscripts so that they could be easily introduced into a particular organum setting or piece of plainchant. As they were notated separately, it was possible for them to be expanded and developed further, and they eventually became standalone pieces which could be sung at certain points in the liturgy. At that time, there were some clausulae that people liked or were particularly popular, for example, those composed on the tenor REGNAT from the verse of the Ascension Alleluia Hodie Maria virgo in the early thirteenth-century. Over time, the appearance and use of clausula changed little by little, but the images of clausula found in different times and regions still had similar characters. Some clausula matched the melodic lines from the French motet without text. This is an important clue to the eventual transformation of clausula into the form of motet. The composition of clausulae died out in the mid-13th century as they were replaced by motets as the main platform for the development of new compositional techniques. Norman Smith claimed that the music of pre-existing clausulae in three early thirteenth-century Latin motets in the Florence Manuscript resemble each other so much that it's hard to find differences in rhythms between the motet and the clausula, which clearly exists. However the difference reflects the artistic changes that occurred in the process of texting clausula. Obviously, possibilities and usefulness of clausula played a pivotal role in the creation of an important musical genre called the motet. References Ars antiqua