Chang 'e should regret stealing the elixir. Where does it come from and what is the moral the author wants to express?

"Chang 'e should regret stealing the elixir, the sky is blue and the night is bright. "Chang 'e, written by Li Shangyin, means that Chang 'e should regret stealing the elixir of life and staring at the blue sky every night, which is unbearable. This poem uses the story of the Goddess Chang'e flying to the moon to express the feeling of loneliness. Surrounded by the dark and dirty reality, the poet tries to get rid of the secular world and pursue the lofty spiritual realm, which often makes him more lonely. The twin brothers of loftiness and loneliness, as well as the self-worship and self-harm caused by them, have been successfully expressed by the poet in implicit and meaningful language, which is the characteristic of this poem. The whole poem is delicate and sad, with profound implications.