The Huangdi Yinfujing (), 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. Texts 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, "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." The Huangdi Yinfujings date of composition is uncertain. Some scholars believed it existed prior to the Zhou Dynasty (1122–256 BCE), while others believe it is a forgery from the Tang Dynasty (618–907 CE). The traditional Chinese belief, as well as the eponymous title, ascribed this classic to the legendary Chinese sovereign Huangdi "Yellow Emperor". According to literary legend, in 441 CE the Daoist reformer Kou Qianzhi hid the Huangdi Yinfujing in a cave near Mount Song, where it was discovered by the Tang military official Li Quan (fl. ca. 743 CE). Li transcribed the text and published it with his commentary (Yinfujing Jie 陰符經解). There is consensus among contemporary scholars that Li probably forged the text, which is confirmed by the absence of references in pre-Tang sources. Despite this comparatively late date, the Huangdi Yinfujing is considered a Chinese classic, and collections like the Daozang and Siku Quanshu include various editions and commentaries. During the Song Dynasty, the Huangdi Yinfujing was canonized by the Quanzhen "Complete