Niu Jing was ill for three months, and turned into a tiger. Then, when he ate another tiger, he turned back into a human. While he was a tiger, he was unaware that he had been a human; while human, he did not know that he had been a tiger.
Li Rong 李冗, Du yi zhi, 獨異志 (Outstanding Fantastic Stories), 上1.6 (Tale 48):
Li Rong 李冗, Du yi zhi, 獨異志 (Outstanding Fantastic Stories) in Du yi zhi, Xuanshi Zhi 獨異志，宣室志 (Outstanding Fantastic Stories, Stories from the Chamber of Dissemination), edited by Zhang Yongqin 张永钦 and Hou Zhiming 侯志明 (Beijing: Zhonghua shuju, 1983)