新汉英大辞典一叶知秋 [yī yè zhī qiū] You may know by a handful the whole sack.One falling leaf is indicative of the coming of autumn. A small sign can indicate a great trend. A straw shows which way the wind blows.It is a straw in the wind.The falling of one leaf heralds [indicates] the autumn.The fall of one leaf is enough to tell of autumn's arrival.