俱舍論疏 12.38

12.38

On the Śāstra's text, "After this there are further... only then does life span gradually decrease": This is the third major section, explaining the kalpa of abiding. Within it there are five parts: first, explaining the order of formation; second, explaining that the beginning is solely decreasing; third, explaining the middle decrease and increase; fourth, explaining that the end is solely increasing; fifth, a general summary of the preceding. This is the first. From the formation of the world of sentient beings across nineteen intermediate kalpas, when human lifespan was immeasurable years, gradually down to a single sentient being [born in] the Avīci hell, it is named the completion of the kalpa of formation. From this point onward, human lifespan gradually decreases.