① The operation of Spirit (shen) or of inner Nature (xing), which makes the Neidan process possible. Mental activity produced not by the ordinary mind, but by Spirit.
⊛ The secret of the Fire phases uniquely consists in the True Intention (zhenyi). Essentially, thoughts should not arise; if they arise, the Fire would scorch. The Intention should not disperse; if it disperses, the Fire would chill. No single thought should arise, and the single Intention should not disperse. One should time their movement and their quiescence, and control their cold and their heat. This is how one should practice the Fire phases. 火候之秘，只在真意，大約念不可起，念起則火燥；意不可散，意散則火冷。只要一念不起，一意不散，時其動靜，察其寒溫，此修持行火之候也。 (Awakening to Reality, "Cut-off Lines", poem 27, Comm. Zhu Yuanyu)
⊛ Within one day, during the twelve hours, wherever the Intention goes, all can be done. 一日內，十二時，意所到，皆可為。 Comm. Wang Jie: The Intention is the operation of one’s Nature (xing); it is the True Soil. . . . Moreover, Water and Fire are divided between North and South, and Wood and Metal are separated between East and West. How can these four images be joined? You must avail yourself of the Intention in order to move through the ebb and the flow. 意者，性之用，即真土也。. . . 且夫水火間于南北，木金隔於東西，此四象何由而合？必假意以通消息。 Mirror for Compounding the Medicine, poem 15)
⊛ The Intention is the operation of Spirit; the so-called True Intention (zhenyi) means that the thought activity issues from the Spirit. . . . If one controls the joining of the Three Treasures (i.e., Essence, Breath, and Spirit) by means of the Intention, then one can activate its intermediary function among the Three Treasures. For this reason, the Intention is also called “go-between” and Intention-Soil (yitu). (Wang Mu, Foundations of Internal Alchemy, p. 40)