世态炎凉

Origin and story

Warmth and cold become an image for changes in people's treatment of one another. In a Tang poem responding to a poem about pine trees, Bai Juyi contrasts the pine's endurance through ice and frost with another tree's changing appearance. He compares that change to the face of an unreliable person responding to warmth and cold.

The exact combined expression is documented in Wen Tianxiang's Song poem Du Jiage, where social ties divide according to wealth and rank. These are poetic judgments about unstable human relations, not descriptions of literal weather. The idiom commonly expresses disappointment when welcome disappears with someone's influence or prosperity.