三彌勒經疏 1.36

1.36

Question: How is it known that the appearance of the Buddhas in the world is only for the duration of half a kalpa? Answer: Although there is no definitive text, by analogy it must simply be so. Another interpretation: The preceding Buddhas appear in the first ten kalpas, and the last, Rucika, appears in the eleventh kalpa, up to the remaining nine kalpas, which are all covered by the bequeathed Dharma of Rucika. If one explains it in this way, ten kalpas are called one kalpa, and in contrast to these latter ten kalpas, it is tentatively called half a kalpa; this meaning is also without fault.