Mirror of Alchemical Insight 丹论诀旨心鉴

Composed by Zhang Xuande, a Taoist priest during the late Five Dynasties and early Northern Song Dynasty. It is recorded as a one-scroll work in both the Secret Catalogue of the Southern Song Dynasty and General Records·Bibliographic Outline.

The existing one-scroll version in the Daoist Canon (The Daozang) is included in the Alchemical Arts Category of the Dongshen Section.

Additionally, this text is also collected in Volume 66 of Yunji Qiqian (Seven Tablets of the Cloudy Satchel). Quoting alchemical scriptures and verses from previous scholars, the book expounds the essential principles of cultivating the Returning Elixir. It is divided into five chapters.

Mirror of Alchemical Insight

Chapter One, Prefatory Secret Instructions, argues that the supreme medicines for the Returning Elixir are lead and mercury, rather than the "Four Yellows" and "Eight Stones" (mineral medicines). It states that the Great Elixir is formed by the profound, primal, and true Qi (Vital Energy) of heaven and earth, and the key to elixir refinement lies in following the principles of Yin and Yang and the Five Elements. If mineral medicines are used for elixir refinement, they will be toxic and unfit for consumption.

Chapter Two, Chapter of Clear Discrimination, discusses the Yin-Yang properties of gold and stone medicines, as well as the theory of matching lead and mercury as the sovereign and minister medicines (a traditional Chinese medical analogy for principal and auxiliary ingredients).

Chapter Three, Treatise on the Golden Elixir, verifies the efficacy of ingesting the elixir to attain immortality. It also quotes alchemical texts such as Cantongqi (The Unity of the Three) and related verses to describe the secret essentials of elixir refinement.

Chapter Four, The Core Tenet of the Great Returning Elixir, elaborates on the cosmic laws governing the gestation and formation of the "Natural Returning Elixir" by heaven and earth, asserting that mortal alchemists should imitate these natural laws in their practice.

Chapter Five, Xuanji’s Record of Chi Songzi, argues that the lead and mercury contained in cinnabar are the essence of heaven and earth. It further emphasizes that the success of elixir refinement depends on one’s mind: "If the mind is enlightened, the medicine will naturally be effective; if the mind is deluded, the medicine’s effects will be unpredictable."