Fox Spirits of the Taiping Guangji · Chapter 1 of 83
On Foxes
说狐
Li Fang, chief compiler · 1 min read

When a fox is fifty years old, it can transform itself into a woman. At a hundred it becomes a beautiful woman, or a spirit medium, or else a grown man who lies with women. It can know what happens a thousand li1 away, is skilled in gu sorcery and bewitchment,2 and makes people lose their wits and their judgement. At a thousand years it communicates with Heaven and becomes a Heavenly Fox.3
From the Xuanzhong ji (玄中记, Records of the Mysterious Centre).