Dà huán xīn jiàn 大還心鑑

Heart-Mirror of the Great Reversion

Anonymous; Five Dynasties

A Five-Dynasties alchemical summary-text on the great-reversion elixir (dà huán 大還 = dà huán dān 大還丹), framed as a “heart-mirror” (xīn jiàn 心鑑). Preserved as DZ 936 / CT 936 (Dòngshén bù, Zhòng shù lèi 洞神部眾術類).