Once, a man went to a library. There he read a book, ‘How to ride a horse’. After few days, he went to a friend who had a horse.. seeing it, he couldn’t control himself and asked for a ride from his friend. The friend agreed.
The man tried to ride the horse. But a horse always recognizes its rider. It reared up and flung the man to the ground.
The friend asked, “Where did you learn to ride?“ the man exposed his foolishness saying that he learnt it from a library book.
One must remember that one can’t learn anything by oneself. You need a teacher if you want to learn.