大乘起信論義記 3.211

3.211

初、明用甚深非待作意，如《攝論》云「如摩尼天鼓，無思成自事」等。二、即與真如等遍一切處者，顯用廣大，以稱理之用故。三、「又亦」下，明用而常寂。於中，何以故者，責云：佛具三身，何故乃云無有用相？釋云：若廢機感，如來唯是妙理本智，更無應化世諦生滅等相；但隨緣起用，用即無用，如波即水，故用恒寂也。《涅槃經》云「吾今此身即是法身。」梁《攝論》云「唯如如及如如智獨存，名為法身。」故云謂諸佛如來乃至離於施作也。雖真理妙智本來常湛，而隨機感益用無邊，即寂而常用，故云但隨眾生乃至為用。別釋用中二：先標、後釋。釋中亦二：初、正顯用相；後、問答釋疑。前中亦二：一、直顯其用；二、重牒分別。前中二：先明應身，後明報身。

First, it clarifies that the function is extremely profound and does not depend on intentional thought, as the Mahāyānasaṃgraha states: "Like the mani jewel and the heavenly drum, without thought accomplishing their own tasks," and so forth. Second, "which are equal to tathatā and pervade all places" reveals that the function is vast, because it is a function that accords with the principle. Third, below "yet there are also..." clarifies that functioning, it is constantly tranquil. Within this, "Why is this?" questions: "The Buddha is endowed with three bodies; why then say there are no marks of function?" The explanation states: If one puts aside the resonance with the faculties of beings, the Tathāgata is solely the marvelous principle and fundamental wisdom, with no further marks of arising and ceasing of the worldly truth of responsive and transformative [bodies]; only in accordance with conditions is function arisen, and function is precisely non-function, just as waves are precisely water; hence the function is ever-tranquil. The Nirvāṇa Sūtra states: "My body at present is precisely the dharmakāya." The Liang translation of the Mahāyānasaṃgraha states: "Only tathatā and the cognition of tathatā remain alone, which is named the dharmakāya." Hence it is said: "Because all Buddhas and Tathāgatas... free from deliberate action." Although the true principle and marvelous wisdom are originally always serene, yet according with the resonance of beings they benefit with boundless function, which is constantly functioning while precisely tranquil; hence it says: "only in accordance with sentient beings... spoken of as function." In the particular explanation of the function there are two: first, setting forth; then, explaining. Within the explanation there are also two: first, directly revealing the marks of the function; then, question and answer resolving doubts. Within the former there are also two: 1. directly revealing its function; 2. repeating and differentiating. Within the former there are two: first, clarifying the response body; then, clarifying the reward body.