What is the key explanation?

A rather critical explanation is to know the arrival of autumn from the fall of a leaf.

1, a yellow leaf fell from the tree, followed by an autumn wind. This is really important.

2. At a critical time, with the rain falling, pieces of brown plane leaves were knocked off and quietly fell to the ground, ready to be absorbed by the mother tree and start a new life.

I saw the fallen leaves flying and falling to the ground. Crucially, the autumn wind blew up my homesickness.

Quite a key introduction:

Quite critical (pinyin: yīyèzhèqi) is an idiom in China, which comes from "Huai Nan Zi Shuo Shan Xun". The original meaning of "quite critical" is to know the arrival of autumn from the falling of a leaf, and then show the development trend and result of the whole situation through individual subtle signs; Generally used as an attribute in sentences.

Idiom story:

At the end of the Warring States period, there was a hermit named Tian Jizi who lived in the deep mountains. He planted a small piece of land near his home and stayed there all the time except buying daily necessities. One day, Zhao's nobles came to the mountain to play. He heard from people nearby that there was a hermit on this mountain, so he came to have a look.

During the chat between Zhao Zheng and Tian Ji, he found that although Tian Ji seldom went down the mountain, he knew the world events and could speculate what would happen in the future. He couldn't help but ask curiously, "Mr. Wang doesn't have to go down the mountain, but he can know what's going on in the world." Is Mr. Murphy a fairy or a powerful divination master? "

At this moment, I saw Tian Ji laughing and saying, "I am neither a fairy nor a fortune teller. I will only calculate the subsequent development and results from subtle signs. " Just as we see the leaves fall, we know that autumn is coming and the weather will get colder and colder.

Seeing that Qin destroyed South Korea, I knew that Zhao could not be saved. Sir, listen to my advice, don't go back to China, stay here! "Soon after, Qin did destroy Zhao, and then destroyed other countries one after another.