It is not true to send charcoal in the snow to see the truth. The allusion comes from Ming and Luo Hongshen's "Awakening the World". The following is an excerpt:
People don't meet as well as at the beginning, and how many virtuous people are in trouble.
There are icing on the cake, but there are many wonders in the world.
It's easier to get 1200 pieces of gold than a pot of wine on credit.
I can't help sighing that my relatives and friends are willing to help when they are in a hurry.
When you describe human nature, it means that when you are high-spirited and proud of your life, many people will think that maybe you will want something in the future, so it is good to have a good relationship with you now. When you are at the bottom of your life, people are afraid that you will ask them for help and avoid it. It is the innate nature of living things to seek good fortune and avoid evil.
Extended information "Send charcoal in the snow" original "Send charcoal in the snow". "Giving charcoal in the snow" means giving charcoal to people who are frozen by heavy snow to make a fire to keep warm. This is a way of caring for others.
According to the History of Song Dynasty. Volume 5 "The Biography of Emperor Taizong" In February of the fourth year of Chunhua, Song Taizong, the rain and snow continued, and the weather was extremely cold. Emperor Taizong sympathized with the lonely people at that time, so he sent people to send money, rice and charcoal. This is an example of "sending charcoal in the snow".
Fan Chengda, a poet in the Song Dynasty, wrote a poem "Sending charcoal in the snow, hiding mustard seeds", which tells the story of giving charcoal to friends in the snow. There are two sentences: "Don't give charcoal in the snow, just talk about scenery and poetry." It means that you didn't really come to give charcoal, but took the opportunity to ask for poetry. This kind of practice, obviously to help friends, but left room for friends, worthy of respect.
Judging from these stories, "offering timely help" is often used to mean helping others when they are in trouble. Documents earlier than the Song Dynasty can be found in the Four-character Classic written by the master Dechan in the Tang Dynasty, among which there is a saying of "giving charcoal in the snow". This idiom is often used with "icing on the cake" and can also be used as a reference. Later, the idiom "giving charcoal in the snow" may have evolved from here, which is used to mean giving timely help when people encounter difficulties and crises.