法界次第初門 3.179

3.179

次相好而辯八音者，若佛以相好端嚴，發見者之善心；音聲理當清妙，起聞者之信敬，故次相好而明八音也。此八通云音者，詮理之聲謂之為音。佛所出聲，凡有詮辯，言辭清雅，聞者無厭，聽之無足。能為一切作與樂拔苦因緣，莫若聞聲之益，即是以慈修口，故有八音清淨之口業。

The reason why the eight voices are discussed after the major and minor marks is that while the Buddha, with the dignified and magnificent major and minor marks, arouses wholesome thoughts in those who behold him, his voice must naturally be pure and marvelous so as to generate faith and reverence in those who hear it; therefore, the eight voices are clarified after the major and minor marks. The reason why these eight are collectively called 'voices' (yīn) is that a sound that expresses principle is called a 'voice'. Any sound uttered by the Buddha that provides explanation and discernment uses language that is pure and elegant, such that those who hear it never grow weary and never tire of listening. As for being able to serve as the causes and conditions for giving bliss and removing suffering for all, nothing compares to the benefit of hearing his voice. This is to cultivate speech through compassion; hence, there is this pure vocal action of the eight voices.