A Treatise on the Mystical Framework 宗玄先生玄纲论

Written by Wu Yun, a Taoist scholar of the Tang Dynasty, this work was already recorded in Book of Tang·Bibliography of Arts and Literature. The version in The Daozang is one volume, included in the Taixuan Section.

As an important theoretical work of Taoism in the Tang Dynasty, it opens with Memorial Presenting the Xuan Gang Lun written by Wu Yun in the thirteenth year of the Tianbao reign period (754), and concludes with Biography of Master Wu compiled by Quan Deyu, Minister of Rites. The main text is divided into three parts—Upper, Middle, and Lower—summarizing the core principles of Taoist theory, hence the title Xuan Gang Lun (Treatise on the Profound Outline).

A Treatise on the Mystical Framework

The Upper Part, Illuminating Dao and De, consists of nine chapters, elaborating on the fundamental meaning of "Dao and De". It states that The Dao is "the link of emptiness, the root of creation, the origin of spirit and intelligence, and the source of heaven and earth"; De (Virtue) is "that which heaven and earth embody, and yin and yang rely on". It further claims: "Pervading and generating all things is called Dao; nurturing and completing all things is called De." Heaven, earth, humans, all creatures, immortals, ghosts, and spirits all take Dao and De as the fundamental source of their existence. Although humans are born from Dao and endowed with De, their inherent nature stirs to produce emotions, and emotions go against Dao—thus life span, birth, and death are beyond one’s control. If one can abandon desires, discard excessive cleverness, act with non-action and without worries, attain the utmost tranquility and emptiness, transcend movement and stillness, and keep spirit, Qi, and body intact, they will unite with Dao, become companions of the Creator, and be free from the burdens of life and death. It also argues that the way of governing must "uphold Dao and De internally and benevolence and righteousness externally, prioritize simplicity and primitivism before ritual and wisdom". Some people mistakenly believe that Taoism belittles benevolence, righteousness, ritual, and wisdom, and solely advocates emptiness and tranquility—this is because Confucian scholars of the time failed to understand the profound meaning of the mysterious sages.

The Middle Part, Distinguishing Dharma and Teaching, comprises fifteen chapters, expounding the essential principles of learning Dao to become an immortal. It states that the path to immortality "takes extreme tranquility as its foundation, quiet contemplation as its application, fasting and abstinence as its duty, and kindness and benevolence as its priority". Then, through breathing exercises (tuna) and guiding techniques (daoyin), one can nourish the spirit and moisten the bones, refine yin with yang, and make yang flourish while yin fades. Although the body may move, it does not hinder the peace of the mind; although practicing non-action, one must not be unobservant. Additionally, one must accumulate hidden merits and rectify visible faults. If the five desires do not stir the mind, clothing and food are left to nature, one absorbs the harmonious primal Qi, and remains awake day and night, they will naturally attain Dao and become an immortal.

The Lower Part, Resolving Obstacles, includes nine chapters, using hypothetical questions and answers to resolve various misunderstandings and obstacles regarding cultivating to become an immortal. It argues that whether one can become an immortal depends solely on their dedication and concentration in learning Dao—even those born with immortal bones can attain immortality while holding official positions and governing the world. Those who uphold loyalty, filial piety, integrity, and chastity, and have rendered great meritorious service to all creatures, will naturally be promoted to celestial positions. It also advocates that cultivating nature and refining the body are equally important and cannot be neglected. Those who only regard attaining nature as wonderful but ignore refining the body are "merely pure, ethereal, and intelligent ghosts—how can they be compared to noble immortals!" This is an implicit criticism of Buddhist doctrines.