Inner Canon of the Yellow Emperor includes two parts, one is called Ling Shu(灵枢), and the other is called Su Wen(素问). Each of them has 9 volumes, and each volumes has 9 articles. That means both Ling Shu and Su Wen has 81 articles respectively.
Inner Canon of the Yellow Emperor finished during Chunqiu period. It includes the relationship between human and nature, physiology, pathology, diagnose, treatment and prevention.
Su Wen tells us something about viscera and bowels, meridian, etiology and mechanism，symptom，diagnose，treatment and acupuncture.
Ling Shu contains not only almost the same as Su Wen， but it still contains shu point, acpuncture tool, how to acupuncture, and principle of treatment.
Both of the books present the theory of yin-yang and five elments（mental, wood, water, fire and soil）.This theory emphasizes the importance of a right time, a proper condition and a good relationship. It shows that our human beings can not live alone without environment.