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 and yang creative energy divides and whose fusion in physical matter brings the phenomenal world into being. Also "attrib." or as "adj." Cf. yin. b. "Comb.": yang-yin = "yin-yang" s.v. yin b. For the earliest recorded "yin and yang" usages, the "OED" cites 1671 for "yin" and "yang", 1850 for "yin-yang", and 1959 for "yang-yin". In English, "yang-yin" (like "ying-yang") occasionally occurs as a mistake or typographical error for the Chinese loanword "yin-yang"— yet they are not equivalents. Chinese does have some "yangyin" collocations, such as 洋銀 (lit. "foreign silver") "silver coin/dollar", but not even the most comprehensive dictionaries (e.g., the "Hanyu