The text written below the _alleluia_ melody is generally accepted as of French origin and likewise the naming of that text. As the text became important the melody too was named so that the melody and text were differentiated from each other, the latter as a _prosa_. It is unknown whether the name _sequentia_ instead of _prosa_ was chosen deliberately as differing from the French usage. Amalarius was apparently the first to use the word _sequentia_ in connection with the music. Later the term was destined to supersede the name _prosa_ for the poetical text. We owe to Notker, whose part in creating the sequence will be considered in greater detail below, an account of his invention of words as an aid to memorizing the elaborate melody of the _alleluia_ trope. Whether Notker was the first to see the value of this device and to employ it, is unknown.[17] As a theory of origin it has always been popular, being held by Frere and many others. For the present it may be acknowledged that it is a reasonable theory for, of course, only the choir leader had a musical codex to refer to and the musical ability of the average monk was unequal to the difficulties of memorization by ear alone. Moreover, this theory can always be accepted with others, although it seems inadequate by itself. A second explanation of origin arises from the possibility that sequence poetry originated in the imitation of Greek hymn models. The statement has been made definitely that sequence poetry shows the transference of the Byzantine structure of hymnody to Latin church poetry, especially Notker’s.[18] With every circumstance favoring such a transfer it is amazing that the Franks who heard so much of Greek hymns and could have translated them into Latin and sung them to the same tunes, evidently did nothing of the kind. Some other explanation of similarity must be found. Metrical parallelism, which is characteristic of the Latin sequence and contemporary Greek hymns, in Gastoué’s opinion, can be accounted for only by reference to Hebrew poetry as the ultimate inspiration of liturgical poetry.[19] Thus a Byzantine theory of origin breaks down when metrical sources are subjected to closer scrutiny. After all, the sequence is unknown in the Byzantine ritual and therefore the Byzantine influence could never have been direct.