Ending of Alchemist

The metaphorical treasure that the boy finds in the end is that in order to realize what you have, you need to experience something more. The boy could have been a simple shepherd and been content, but he would have never truly realized the full extent and possibilities of his life without having gone through the trials that he underwent.

I took his knowledge of the language of the world to mean that he learned that all things in this world are connected, somehow. That, too, was a treasure.

But as for the physical treasure? It was waiting for him all along in the abandoned church at the beginning, meaning that the treasure was there all along. He only needed to know how to look for it.