大毘盧遮那成佛經疏 14.42

14.42

如是祕密主！字道門善法真言道住次第，諸佛神力加持三藐三佛陀道菩薩行舞者，經云如是，即指上字輪也。如上來所說定慧空等，即是佛道之門，能成正覺之道也。若了知字義，即能住於真言之道，其中次第法則、證入之相、階位差別亦悉曉知，明達通塞無有疑滯也。然此悉曇字母，乃至世間童子亦常修習，何能頓辦如是事耶？然此諸字，皆是如來以加持神力從如來內證體性而流出之，故能有是不思議業用。若人明解此中意趣方便，即是通達三菩提道也。善能通達者，謂達一切眾生諸根性欲，當以何法而得入道、當從何門而得曉悟，如是等無量無邊皆能了知。而隨眾生受與妙法，皆令得至如來之地也。舞者，如世人舞，而於大眾中動種種身業屈申俯仰，又出種種微妙巧便之音曲，順眾生之所欲樂。彼大眾或令歡喜、或令悲思、或令恐怖，以一身口所出方便，令諸眾生所益不同，由彼善知去就，能順眾生心故。菩薩亦爾，現種種威儀無不成印，出種種妙法音皆是真言，圓應無方皆得大利，故名菩薩舞也。

Regarding "Thus, Secret Lord! The wholesome dharma mantra-path of the syllable-course gateway abides in sequence, empowered by the supernatural powers of all buddhas, the samyaksaṃbuddha-path, the dancing of the bodhisattva practices": when the sūtra says "Thus", it points to the syllable-wheel above. As explained above, samādhi, wisdom, emptiness, and the like are the gateway to the buddha-path, the path capable of achieving true enlightenment. If one fully understands the meanings of the syllables, one can abide in the path of mantras, fully knowing its sequential rules, the marks of realization and entry, and the distinctions of stages, lucidly penetrating what is unobstructed and obstructed without doubt or hesitation. However, these Siddhaṃ vowels and consonants are practiced even by worldly children; how could they abruptly accomplish such matters? These syllables all flow forth from the tathāgata's nature of inner realization through the tathāgata's empowered supernatural power; therefore they can have such inconceivable operations. If a person clearly understands the intent and upāya herein, that is penetrating the path of saṃbodhi. "Skilled in penetrating" means penetrating the capacities, natures, and desires of all sentient beings, thoroughly knowing by what dharma they can enter the path, and through what gateway they can attain realization, understanding immeasurable and boundless such matters. Conforming to sentient beings, one bestows the wondrous Dharma upon them, causing them all to reach the tathāgata-stage. "Dancing": like a worldly person dancing, who moves with various bodily karmas of bending, extending, bowing, and looking upward in the midst of a great assembly, and utters various subtle, skillful melodies and songs, adapting to the inclinations and pleasures of sentient beings. He makes that great assembly feel joy, or sorrowful reflection, or terror; through the upāya produced by a single body and mouth, he causes the benefits of sentient beings to be diverse, because he is skilled in comportment and able to accord with the minds of sentient beings. The bodhisattva is also like this: manifesting various deportments, none of which fail to become mudrās; uttering various wondrous Dharma sounds, all of which are mantras; responding completely and without bounds, all attaining great benefit; hence it is called the bodhisattva dance.