唐无名氏有句曰:“山僧不解数甲子,一叶落知天下秋。”(宋人唐庚《文录》、陈元靓《岁时广记》卷三引)意谓久居深山里的僧人不知道去数日历计算岁月时令,但只要看见树上落下一片叶子,便知道秋天已经悄然来临。一叶知秋,语本《淮南子·说山训》:“以小明大,见一叶落而知岁之将暮 Tang anonymous saying: “Shan monk does not understand the number of Jia Zi, a leaf falls to know the world autumn.” (Song Tang Geng “records”, Chen Yuan Liang “age Guangji” volume three cited) means living in the mountains monks not Know to count the calendar to calculate the years of seasonal, but as long as saw the tree falling a leaf, we know that the fall has quietly come. A leaf known autumn, the language “Huainanzi said mountain training”: "small Mingda, see a leaf fall and the old will be twilight