A young father was visiting an old neighbor. They were standing in the old man's garden,and talking about children. The young man said,"How strict should parents be with their children?" The old man pointed to a string between a big strong tree and a thin young one."Please untie that string," he said.The young man untied it,and the young tree bent over to one side. "Now tie it again,please," said the old man,"but first pull the string tight so that the young tree is straight again." The young man did so.Then the old man said,"There,it is the same with children.You must be strict with them,but sometimes you must untie the string to know how they are getting on. If they are not yet able to stand alone,you must tie the string tight again.But when you find that they are ready to stand alone,you can take the string away." The young man untied the string   _  .
in order to throw it away so that both of the trees would grow straight only to find that the thinner one bent over to one side in order to let the old man teach him