元稹《乐府古题序》:“(操引谣讴歌曲词调)八名皆起于郊祭军宾吉凶苦乐之际,在音声者,因声以度词,审调以节唱,句度短长之数,声韵平上之差,莫不由之准度,而又别在琴瑟者。……斯皆由乐以选词,非由调以选乐也。”“(诗行咏吟题怨叹章篇)九名皆属事而作。虽题号不同而悉谓之为诗,可也。后之审乐者,往往取其词度为歌曲,盖选词以配乐,而非由乐以定词也。”①按,“由乐以选词,非 Yuan Zhen ”Yuefu ancient title“: ”(to guide the rhyme song song tune) Eight are from the suburban military Bingji auspicious music occasion, in the voice, due to the sound of the degree words, the trial to sang, Sentences are short and long, the difference between the phonological level, not by its accuracy, but do not be in the singer. Line chant Yin title complain sigh chapters) nine are all things and make .Although the title number is different and that is poetry, can also .After the musicians, often take the degree of its lyrics, , But not by the music to determine the word also. “① Press, ” by the music to choose words, non