Neidan Dictionary
xin 心
heart; mind; center
① One of the five viscera of the human body in the system of the five agents (wuxing). Main associations: Fire; South; summer; red. See Table Five Agents.
⊛ The heart is red and is the daughter. 心赤為女。 (The Seal of the Unity of the Three, sec. 72)
② Yang. ↔ shen 腎 kidneys.
⊛ The heart is Yang, the kidneys are Yin. 〔陽:〕心。〔陰:〕腎。 (Weng Baoguang, "Model Images of the Golden Elixir", trans. in Taoist Internal Alchemy: An Anthology of Neidan Texts, p. 123)
③ The residence of Spirit (shen).
⊛ The heart stores the Spirit. 心藏神。 (Daode jing, sec. 6, comm. Heshang gong)
⊛ When the Spirit is in the heart, it does not leak through the mouth. 神在心而不從口漏。 (Four Hundred Words on the Golden Elixir, Preface)
⊛ The Heart is the dwelling of Spirit; if the Heart is luminous, the Spirit is clear; and if the Spirit is clear, one’s Nature (xing) is stable. 心為神舍,心明則神清,神清則性定。 (Liu Yiming, Cultivating the Tao, chap. 5)
④ The middle Cinnabar Field.
⊛ The brain is the upper Field, the heart is the middle Field, the Ocean of Breath is the lower Field. 腦為上田,心為中田,氣海為下田。 (Xiao Tingzhi, Questions and Answers on the Golden Elixir)