The little girl Xiaoxing discovered a secret - the reason why the moon waxes and wanes is because an old woman is making clothes for it.
As the moon becomes fatter and thinner, the clothes must be constantly modified. Xiaoxing took over the job and used starlight and heart to sew the moon's clothes.
And what was sewn into the moonlight was her tenderness that wanted everyone to have a good dream.
Purpose: love and protection