佛祖統紀 30.55

30.55

As for the great three disasters: at the end of each great kalpa, a disaster of fire must arise (as described above, the eighty small kalpas of formation, duration, destruction, and voidness of the Fortunate Kalpa constitute one great kalpa). After seven great kalpas and seven fire disasters pass like this, having destroyed the First Dhyāna seven times in all, another great kalpa passes and a water disaster arises, destroying up to the Second Dhyāna. Thus, seven times seven fire disasters alternate with seven water disasters; then after another seven fire disasters, in all fifty-six rounds of fire destroy the First Dhyāna, and seven rounds of water destroy the Second Dhyāna. When yet another great kalpa passes, a wind disaster arises. In total, this makes sixty-four great kalpas, which constitutes the full sequence from beginning to end of the three great disasters (the meaning is derived from the Abhidharmakośa-bhāṣya).