法苑珠林 4.49

4.49

又何因緣月天宮殿漸漸現耶。佛答。此月三因緣。一背相轉。二青身諸天。形服瓔珞一切悉青。常半月中隱覆其宮。以隱覆故月漸而現。三從日天宮殿有六十光明一時流出障彼月輪。以是因緣漸漸而現。

"Furthermore, by what cause and condition does the Moon Deva's palace appear gradually?" The Buddha answered, "There are three causes and conditions for this moon: first, its back turns toward [us]; second, there are devas with blue bodies, whose forms, garments, and necklaces are all blue, and they always conceal its palace during half of the month—because of this concealment, the moon appears gradually; third, sixty rays of light flow forth at one time from the Sun Deva's palace and obstruct the lunar orb. Due to these causes and conditions, it appears gradually."