There was a fisherman who had first-class fishing skills and was respected by people as the "King of Fishermen". However, when the "King of Fishermen" was old, he was very distressed because the fishing skills of his three sons were all mediocre.
So he often told others about the distress in his heart: "I really don't understand. My fishing skills are so good. Why are my sons so bad?
I have taught them fishing skills since they were sensible. I started teaching them from the most basic things, telling them how to weave nets to catch fish most easily, how to row boats to least disturb the fish, and how to cast nets to most easily trap the fish. When they grew up, I taught them how to recognize tides and predict fish seasons...
I have imparted to them without reservation all the experiences I painstakingly summed up over the years. But their fishing skills are not even as good as the sons of fishermen whose skills are worse than mine!"
After listening to his complaint, a passer-by asked, "Have you been teaching them hand in hand all the time?"
"Yes. In order to let them acquire first-class fishing skills, I taught them very carefully and patiently."
"Have they been following you all the time?"
"Yes. In order to let them avoid detours, I have always let them learn from me."
The passer-by said, "In that case, your mistake is very obvious. You have only imparted skills to them but not lessons."