法苑珠林 4.65

4.65

According to the Lokotpatti-sūtra: The Buddha told the monks, 'If non-Buddhists come and ask you, "By what cause and condition does lightning suddenly flash in the sky?", you should reply, "By two causes and conditions lightning issues from the clouds. What are the two? First, in the east there is lightning called Thickness-less; in the south there is lightning called Along-the-Current; in the west there is lightning called Falling Light; in the north there is lightning called Hundred-Born Tree. Second, at times the great Thickness-less lightning issuing from the east and that Falling Light lightning of the west collide, face each other, rub against each other, and strike each other; for this reason, from within the cloud-masses in the sky there arises a great illumination, which is called lightning. Or again, the great Along-the-Current lightning of the south and that great Hundred-Born Tree lightning of the north collide, face each other, rub against each other, and strike each other; for this reason lightning arises. It is just as when two pieces of wood blown by the wind strike together, fire suddenly emerges and returns to its source."' (According to the sūtras, sometimes there is first thunder without lightning, or first lightning and then thunder; striking each other, fire issues forth and strikes down people and things.)