大乘起信論義記 2.17

2.17

問：二門既齊相攝者，何故上文真如門中唯示大乘體，不顯於相用？生滅門中具顯三耶？答：真如是泯相顯實門，不壞相而即泯，故得攝於生滅；泯相而不存，故但示於體也。生滅是攬理成事門，不壞理而成事，故得攝於真如；成事而理不失，故具示於三大。

Question: Since the two gates equally subsume each other, why is it that in the text above, the gate of tathatā only reveals the essence of the Mahāyāna and does not display the marks and function, whereas the gate of arising and ceasing fully displays the three? Answer: Tathatā is the gate of eliminating marks and revealing the real; without destroying marks it immediately eliminates them, and hence can subsume arising and ceasing; because it eliminates marks so that they do not remain, it only reveals the essence. Arising and ceasing is the gate of gathering the principle to form phenomena; without destroying the principle it forms phenomena, and hence can subsume tathatā; because phenomena are formed without losing the principle, it fully reveals the three greatnesses.