The townspeople bought a diamond and everyone were happy that they bought the diamond for so little money. But one of them asked if the diamond they had bought was real.
However, none among the townspeople knew about diamonds, so they went to an expert dealer to tell them if the diamond was real or fake. They were happy with his reply that the diamond was real.
But one of them asked if they could trust the dealer, since he could be a crook. Therefore, he himself wants to learn the trade and be an expert in his own right, and he learns and succeeds.
The lesson is that we can believe our engagement in Torah and Mitzvot [commandments] when we rely on faith that we received from books and authors.