A farmer tied an iron ring to the trunk of an elm tree on his farm to facilitate the tying of cattle. As the iron circle of the elm tree grew slowly, the skin of the mathematical elm tree left a deep scar.A year later, it was found that all the elm trees dozens of miles away from elm disease died, but the elm tree which was tied with an iron ring and left a deep scar survived. Botanical studies found that it absorbed a large amount of iron from the rust ring to develop immunity to fungi.
The truth of this passage is that scars sometimes become a nourishment of life.