瑜伽論記 1.454

1.454

光師釋俱舍云：問：初劫唯減、下劫唯增，據何時等，中間十八？解云：二十住劫，前後相望，前有情福勝，後有情福劣。住中初劫、福最勝，應合受用，上妙境界，故下時極遲。從第二劫以去，其福漸薄，上稍遲下漸疾；以上時境勝、薄福故，不合受用，故上時遲；以下時境劣、薄福故，應合受用，故下時疾。如是乃至第二十劫福最薄故，上時極遲，故初後劫等中十八。又解：壽未減時，是成劫攝，無量歲初，減已去方名住劫。第二十劫，上至八萬多，時經停故，初後等中十八。

Master Guang, explaining the Abhidharmakośa, says: 'Question: The first kalpa has only a decrease and the last kalpa has only an increase; on what basis are their durations equal to the eighteen intermediate ones? Explanation: Comparing the twenty dwelling kalpas earlier and later, the earlier sentient beings have superior merit and the later sentient beings have inferior merit. In the first of the dwelling kalpas, merit is supreme, so they ought to experience superior and marvelous realms, and thus the descending time is extremely slow. From the second kalpa onward, their merit gradually diminishes; the ascending time becomes slightly slower and the descending time gradually faster. Because during the ascending time the realm is superior, but due to their slight merit they ought not to experience it, the ascending time is slow; because during the descending time the realm is inferior, and due to their slight merit they ought to experience it, the descending time is fast. Thus, continuing up to the twentieth kalpa, because their merit is the slimmest, the ascending time is extremely slow; hence the first and last kalpas equal the intermediate eighteen. Another explanation: The time before the lifespan decreases is subsumed under the kalpa of formation; only from the initial decrease of the immeasurable years onward is it named a dwelling kalpa. In the twentieth kalpa, it ascends to eighty thousand, pausing there for a long time; therefore the first and last equal the intermediate eighteen.'