It is said that once upon a time there was a great mountain, called the Sun and Moon Mountain (Rìyuè Shān 日月山), where there lived clever and beautiful maiden named Chángxī 常羲.
She was indeed so especially clever and beautiful that she came to the attention of the Emperor of Heaven (Tiāndì 天帝), who married her, and to whom she bore twelve children, each of whom grew up to be a moon. Of course, the word “moon” also means “month” —both are yuè 月. So one could also say that each child grew up to be a month. But that would be silly. Or would it? Read on:
She kept each child carefully bathed and dressed in clean clothes, and she let each in turn ride the great silver chariot of the sky. Thus we see twelve moons/months each year, succeeding each other in good order.
It is said that there is a great toad who lives in the moon. In the first half of every month he vomits out a bit of the moon, so that by the 15th we can see it round and full. But in the second half of each month he devours it again, so that by the 1st of each month it is all gone.
Some say they can see a jade rabbit living on the moon, who prepares the elixir of immortality (xiānyào 仙药) in a great cauldron.
When he has finished it, he will distribute it to people who believe in the celestial gods, and they will become immortal. Perhaps it is because of this promise that so many people say they can see the rabbit.
WÚ Gāng 吴刚 sought to become an immortal, but in the course of his studies made a careless mistake that offended heaven, so he was banished to the moon, where it was made his punishment to cut down a magical cassia tree five thousand feet tall.
Unfortunately with each stroke of the ax, the tree heals immediately, so Wú Gang is visible up there to this day, chopping away at the tree as he works out his endless punishment.