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
Yang Yin Yang Yin Yang Yin (楊愔) (511–560), courtesy name Zhunyan (遵彦), nickname Qinwang (秦王), was a high-level official of the Chinese dynasty Northern Qi. Yang Yin came from a clan that produced many officials of Northern Wei. His father was Yang Jin, and his mother was Yang Jin's wife Lady Yuan, who came from a noble lineage herself, being the granddaughter of the famed official Yuan He. In his youth, he studied the histories, the "Shi Jing", and the "I Ching", but particularly favored the "Zuo Zhuan" version of the "Spring and Autumn Annals". In 526, during the reign of Emperor