There once was a tree who was very young and very short like most trees. He wanted to grow up and be big and strong but most trees died when they got tall because they're insides had no protection from the sun.
When the man realized he would not be alive for much longer he went back to visit the little tree to see if his bark had worked. He saw that the young and short tree was no longer short but was now tall and he was resisting the light of the sun. The bark the man had put on the tree had become a part of the tree and the tree had started to make its own bark. The tree thanked the man for allowing him to grow up big and strong.
The man realized he would not be alive for much longer so he set out to coat as many trees with bark as he could. When he finished, he died. But when the man died he was happy because he knew he had done a very good deed.
A man came along and he saw that the trees could not grow up to be big because of their lack of protection. He was grieved that trees could not live a long time like him. So the man took some sap from a dead tree and he cut the tree into wood scraps he called "bark." He then took the bark and he glued it to the young tree using the sap. The young tree thanked the man for his efforts and the young tree was ecstatic that he would be able to grow up to be tall and strong.
The man became ill one day and he did not go out for a long time.
Eventually all the trees with no bark died off and the only trees that where alive where the trees with bark. Today Trees still have their bark to protect them from the sun.