Treatise on the Five Elements

During such times, rain is scarce and the sky is often overcast. If the celestial qiCelestial and terrestrial "qi" (氣) are the dual atmospheric energies that traditional Chinese science believed governed all natural phenomena. has already descended and the terrestrial energy has risen, but the two have not yet intermingled: the sun will appear green. If this occurs at night, the moon will appear deep green. This is a sign of an impending cold spell.

Alternatively, if the celestial and terrestrial energies have intermingled but are not yet dense: the sun will appear black, or if at night, the moon will appear blue-green. This indicates that it is about to rain, yet the rain will not fall; instead, the weather will turn into falling mist, halos, parheliaoriginal: 暈背 (yùn bèi). These refer to complex optical phenomena where rings or arcs of light appear around the sun, often interpreted as atmospheric "shadows" or "reflections" of political conflict., or rainbows.

When the sun gathers the radiance of the five colors, the world is at peace.

If the color of the sun is white and the west wind forms whirlwinds, the yin and yang energies are in disorder; secret conspiracies will arise and military actions will begin. It is also said: if this occurs in the territories of the feudal lordsoriginal: 諸侯 (zhūhóu). These were regional rulers or high-ranking nobles who held land under the Emperor; their actions were critical to the stability of the empire. while two armies are facing each other, then that specific army will be defeated and its general killed. Within one day, the frontier tribesoriginal: 四夷 (sì yí). A traditional term for the ethnic groups living on the four borders of the Chinese heartland, often viewed as a military threat in these texts. will be stirred to movement; within another day, there will be drought or a period of mourning.

If the sun is white and its body appears to tremble and feels cold, the Son of HeavenThe Emperor of China, who was believed to rule by divine mandate and was uniquely responsible for responding to celestial omens. will personally lead a military campaign; this is known as "acting without understanding the signs."