In the field, there was a small animal called “wu shu”(the flying squirrel1).
It would say to everyone it met: “I have five skills: flying, walking, swimming, climbing trees, and digging holes in the ground.”
Thereupon, its pals2 would laugh at it, saying: “Though you have learned these skills, you have mastered none of them. You can fly, but not high; you can swim, but not far; you can climb trees, but not to the treetop; you can dig holes in the ground, but not deep enough.”
When the flying squirrel heard what its pals said, it ran away in anger.
Indeed, the flying squirrel had learned five skills, but when put to use, they were useless. How could they be called real skills.