妙法蓮華經玄贊 2.60

2.60

贊曰：「樂」音五孝反。梵云末奴是若颯縛羅，此云可意音，亦名如意音。樂者令人愛樂也。《正法華》云：「一名柔軟天子，二名和音天子也。」梵云健闥縛，此云尋香行，即作樂神。「乾闥婆」訛也。西域由此呼散樂為健闥縛，專尋香氣作樂乞求故。樂中有二類：一非絲竹也，鼓磬之類；二是絲竹，簫箏之輩。非絲竹之下者名樂，上者名樂音；絲竹之下者名美，上者名美音。或此同前歌神音曲，如次同彼。

The commentary says: The character yue (樂) is pronounced as the fanqie wu-xiao [lè, 'joyful/delightful']. In Sanskrit it is manojñasvara, which means here 'agreeable sound' or 'pleasing sound'. Yue means causing people to love and take joy in it. The Zheng fahua [jing] says: 'The first is named Son of Heaven of Gentle [Sound], and the second is named Son of Heaven of Harmonious Sound.' In Sanskrit it is gandharva, which means here 'scent-seeking traveler', namely spirits that make music; 'gandharva' [in the older transcription] is an error. In the Western Regions, itinerant musicians are therefore called gandharva, because they specifically seek out fragrances, play music, and beg for offerings. Among musical instruments there are two classes: the first is not strings and winds, such as drums and chime stones; the second is strings and winds, such as pipes and zithers. The lower grade of those that are not strings and winds is called 'music' (樂), and the upper grade is called 'musical sound' (樂音); the lower grade of strings and winds is called 'fine' (美), and the upper grade is called 'fine sound' (美音). Alternatively, these correspond to the musical airs of the song spirits mentioned above, matching them respectively.