Huangdi Yinfujing

The Huangdi Yinfujing (Chinese: 黃帝陰符經; pinyin: Huángdì Yǐnfújīng; Wade–Giles: Huang-ti Yin-fu Ching; literally: "Yellow Emperor's Hidden Talisman Classic"), or Yinfujing, is a circa 8th century CE Daoist scripture associated with Chinese astrology and Neidan-style Internal alchemy. In addition, Huangdi Yinfujing is also the name of a Chinese Fengshui text on military strategy.

There are two received versions of the Daoist Huangdi Yinfujing, a shorter text of 332 Chinese characters in one section and a longer one of 445 in three sections. Both versions of this classic explain cosmological correspondences, the Dao of Heaven, Yin and Yang, the Wu Xing, and biospiritual techniques. In the description of Alexander Wylie (1867:216), "This short Treatise, which is not entirely free from the obscurity of Tâoist mysticism, professes to reconcile the decrees of Heaven with the current of mundane affairs." In the explanation of the modern Daoists Zhang Jiyu and Li Yuanguo,

The Huangdi yinfu jing (The Yellow Emperor's Scripture on "Unconscious Unification") reflects this later stage of Daoist thought and attempts to "expose heaven's mysteries and reveal divinity's workings." It became one of the most important classics of Daoism, second only in significance to the Daode jing. Zhang Boduan (987-1082), in his Wuzhen pian (An Essay on Realizing Perfection), said: "The treasured Yinfu jing consists of more than three hundred words whereas the inspired Daodejing has five thousand characters. All those who attained immortality in the past and attain it in the present have comprehended the true meaning of these scriptures." (2001:113)

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