Chinese sun and moon mirrors being hung round the neck, or because necks are concave things. Liu An's (c. 139 BCE) "Huainanzi" "Masters of Huainan", which is a compendium of writings from various schools of Chinese philosophy, was the first text to record "fangzhu" dew-collectors. Two "Huainanzi" chapters metaphorically use "sun and moon mirrors" to exemplify "yang" and "yin" categories and elucidate the Chinese notion of "ganying" "cosmic resonance" through which categorically identical things mutually resonate and influence each other. The "yángsuì" 陽燧 "burning-mirror" is "yang", round, and sun-like; the "fāngzhū" 方諸 "square receptacle" is "yin", square, and moon-like. The first context describes "yangsui" and
Yin Yang Style Li (离), Kun (坤), and Dui (兑) which correspond to and form the changing ways of the Yin and Yang and the Bagua. The postures of crane walking and eagle spanning also correspond to the eight directions: East, West, South, North, Northeast, Northwest, Southeast and Southwest of the Yin and Yang and the Eight Trigrams. The movements also mimic the arc in the Yin Yang Fish. There are eight characters, eight directions, eight body sections, eight steps, eight posture palms, eight energies and eight coincidences. The Python Form Palms of Tian's family Yin Yang Bagua Zhang consists of eight postures: