Watching silk being dyed,
墨子 sighed:
染于苍则苍，
染于黄则黄 (dye it in blue and it turns blue, dye it in yellow and it turns yellow). From that,
苍黄 came to mean a sudden reversal, as in Mao Zedong's
钟山风雨起苍黄 on the fall of Nanjing in 1949. It is also written for
仓皇 (in a panic).
