《太平广记·卷三·神仙三》
王母又让法婴唱起了九天神灵的歌曲，唱完后，王母说： 如果要修炼道术，首先要练运气之功，也就是《太仙真经》中所说的 益、易之道 。所谓 益 ，就是要有益于养精神，所谓 易 ，就是要改变自己的形体。
又命法婴歌玄灵之曲。歌毕，王母曰： 夫欲修身，当营其气，《太仙真经》所谓行 益、易之道 。 益 者益精； 易 者易形。
The Queen Mother had Fa Ying sing the song of the nine gods, and after she finished singing, the Queen Mother said: If you want to cultivate Dao, you must first practice the art of luck, which is what the Scripture of the Great Immortal says is the Way of Benefit and Change. So-called Benefit is that it must be of benefit to nourishing the spirit, so-called Change is that you will change your form.