The San Tian Nei Jie Jing 三天内解经

Originally attributed to "Xu, a Disciple of the Three Caverns".

The author was a follower of the Five Pecks of Rice Taoism during the Liu-Song Dynasty of the Southern Dynasties.

Comprising two volumes, this text is included in the Zheng Yi Bu (Orthodox Unity Section) of the Daozang (Taoist Canon).

The first volume mainly expounds on the myths of the Supreme Lord of the Dao’s incarnation and his descent to the mortal world to propagate the Dao. It proclaims that the Great Dao originally emerged from nothingness, and later incarnated as the Venerable Lord of Dao and Virtue, titled "The Supreme Ultimate Great Dao of the Three Heavens, Pure and Primordial".

The Great Dao generated the Three Primordial Qi (Primordial, Initial, and Beginning Qi), which in turn gave birth to the Mysterious and Wonderful Jade Maiden. The Jade Maiden bore Laozi, who then manifested the Three Qi to create the Three Realms of Heaven, Earth, and Humanity. Laozi also promulgated three doctrines to instruct the people: the Supreme Great Dao was practiced in China, the Buddhist Dao in foreign lands, and the Pure and Ascetic Great Dao in the regions of Chu and Yue.

Later, due to "the degeneracy and impiety of the later ages, the rampant spread of evil and heresy, the prevalence of sacrificial rituals to sham ghosts, and the confusion between truth and falsehood", the Supreme Lord transmitted the Scripture of the Taiping Dao to Gan Ji of Langya and Li Wei of Shu Commandery. By the Han Dynasty, "all kinds of evil flourished, the Qi of the Six Heavens ran amok, the three doctrines became intertwined, pestilential Qi raged everywhere, and sorcerers and shamans abounded". Thus, in the first year of the Han’an era of Emperor Shun (142 CE), the Supreme Lord revealed the "Way of Orthodox Unity and Bright Majesty" and transmitted it to Zhang Daoling, empowering him to enlighten and transform the people.

Because adherents offered five pecks of rice as a token of faith, this school became known as Five Pecks of Rice Taoism. The text also mentions that during the Wei and Jin Dynasties, there existed the Clear Water Taoism, which was passed down by a household servant of the Celestial Master Zhang’s lineage.

Although the above accounts are mythological, they also reveal historical clues about the emergence and evolution of early folk Taoist sects such as the Taiping Dao and Five Pecks of Rice Taoism. The second volume of the scripture expounds on Taoist cultivation theories, which are largely based on Laozi’s Dao De Jing. It exhorts people to contemplate the true nature and uphold the Dao, strengthen their fundamental essence, and preserve the Dao Qi within themselves without losing its origin—by doing so, one can achieve immortality.

The text also discusses the concept of "zhai zhi" (pure fasting and upright conduct), asserting that "pure fasting and upright conduct should be the primary practice for learning the Dao". This practice can purify one’s body from external defilements, cleanse the five internal organs internally, summon true deities and spiritual forces, and ultimately attain unity with the Dao. Additionally, it criticizes the so-called "Hinayana Taoists" of its time, stating that they "wore an excessive number of talismans but performed very few daily devotions" and that they "engaged in verbal disputes while lacking inner concentration". This book exerted a considerable influence on Lu Xiujing’s reform of Five Pecks of Rice Taoism during the Southern Dynasties.