金光明經文句記 3.45

3.45

Third, from 'Of the skandhas' downward, clarifying the characteristics of the substance and function of the three bodies. Dharma and retribution are both doubly negated; their entire substance generates function, capable of permanence and impermanence. When the permanent is functioning, it is long, etc.: long is the four metaphors, and short is eighty [years]. Since both are response lifespans, all are impermanent. Now dividing permanent and impermanent by long and short is because the weight of the mountain and so forth can reveal permanence. If the substance were not permanent, how could the responsive function be innumerable to humans and devas? Therefore, when Ruciraketu heard of cessation at eighty, he doubted that the lifespan was impermanent; when he heard the length of the four metaphors, he awakened to the permanently abiding substance. Thus it is said that when the permanent functions, it is long, and when the impermanent functions, it is short.