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
Taijitu and called the "River Chart spontaneously generated by Heaven and Earth". By the end of the Ming period, this diagram had become a widespread representation of Chinese cosmology. The dots were introduced in the later Ming period (replacing the droplet-shapes used earlier, in the 16th century) and are encountered more frequently in the Qing period. The dots represent the seed of yin within yang and the seed of yang within yin; the idea that neither can exist without the other. Lai Zhide's design is similar to the "gakyil" ("dga' 'khyil" or "wheel of joy") symbols of Tibetan Buddhism; but while