What kind of knowledge is this?

Once there was master who was very knowledgeable. He was very famous for his knowledge. He start to visit many cities while he was a young one.

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That time there were no transportation that time.
That time there is danger of robbers while traveling.One day he was traveling thought the jungle/forest he stopped and was reading.
Suddenly that time a group of robbers came and starting threaten him.

The robbers said handover me all the things that you have said the leader of the robbers, else you have to die.

The master said "I have only clothes and books".
The leader said we don`t need your clothes, we will take your books and sell them. After taking they left.

The master was very sad about his books, what will I do when I have to see something from the books?

He start running towards robbers, and he starting to pray to robbers "this books are very Important to me,if you sell them you will got penny of money.I this books are gone I am nothing.I need this books this books are very important to me, please return this to me."

The leader laughs a lot and then replied, he throw the bag of books and said what kind of knowledge is this? when you don`t have books you have no knowledge. you take your bag, you are not a real master.

The robbers gone to and the master realize that the robber said the truth.
What kind of knowledge is that, which is zero without books.
After this incident the master learn all the books by hard and he made himself a real master.

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Hope you like my post.

@bhattg