Qi (氣)
Vital breath — middle dan tian
Qi (氣) — the middle treasure: vital breath / animating force. Refined from jing in the alchemical sequence and accumulated in the middle dan tian (tanzhong / chest-centre). Qi pervades all bodily and psychic activity in TCM physiology; the san bao distinction is its alchemical-substantial sense, where it sits between the densest (jing) and the most refined (shen). The Cantong Qi's cosmology of yin-yang reciprocity and Five Phase circulation is the template within which qi is understood as the mediating substance.
Point 2 of 3 in Three Treasures (三寶) — Jing / Qi / Shen
Cross-tradition overlaps
No overlapping points are registered for this point.
Sources
Wei Boyang, Cantong Qi (primary_canonical)
Cantong Qi, the Qian-and-Kun and Five Phases sections (Pregadio 2011), frames qi through cyclical yin-yang transformation and phase circulation; this is the cosmological basis for its mediating place between jing and shen.
Huangdi Neijing, Lingshu (primary_canonical)
Lingshu ch. 8 (Ben shen) places qi within the sequence joining essence, spirit, and the mind faculties, documenting its physiological relation to the other substances rather than a fixed middle-dan-tian coordinate.