一切經音義 3.154

3.154

四倒（音到韻詮云顛倒也四倒者涅盤經云無常計常無樂計樂無我計我無淨計淨名為四倒者也）。

四倒 (Four inversions: [倒 has the] sound 到 [dào]. The Yunquan says: 'Perverted, upside down.' As for the 'four inversions', the Mahāparinirvāṇa-sūtra says: 'Regarding the impermanent as permanent, regarding suffering as pleasure, regarding non-self as self, and regarding the impure as pure—these are called the four inversions').