一叶知秋
yī yè zhī qiū
one small sign shows which way things are going
Character by character
一yī
one
one
叶yè
leaf
leaf
知zhī
know
know
秋qiū
autumn
autumn
Example
一叶知秋，街上的老店接连关门，说明生意越来越难做了。
One leaf tells you autumn is here: when the old shops close one after another, business is clearly getting harder.
Tone: neutral.
Usage and origin
From 《淮南子》, the same book that first lists all 24 solar terms: one falling leaf tells you the year is ending.
Learn this in Lesson 215 · HSK 9+: 二十四节气 (The 24 solar terms)
A dialogue, a reading, word cards with audio and a drill that uses it, in Learn Chinese with Bao. The first lessons of every level are free.
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