What does it mean to know autumn by falling leaves?

Pronunciation: Luòyèzh qi Interpretation: It refers to seeing yellow leaves falling to the ground and knowing that autumn is coming. Refers to the development and change of events can be predicted by signs. Source: Songshi Puji's "Five Lantern Festival Yuan" Volume 20: "Leaves fall to know autumn, give Ming San." "Continued Lantern Biography": "The strings move and the leaves fall to know the autumn." Han-Liu An's "Huai Nan Zi Shuo Shan": "When you see a leaf falling, you know the end of the year." Tang Mingzu's "Conan Xia Ji": "I hate the end of the world and shake down three glasses of wine, like falling leaves and knowing autumn." Example: We should be sensitive and be able to see the development trend of a thing from its surface. Synonym: rather critical. Usage: generally used as predicate and object.