once santiago believes he understands his heart,what agreements does he ask for?what does he promise it in return?

Traveling with the alchemist, Santiago learns many things that were merely hinted when he was traveling alone. It is with the alchemist that he finally realizes that his heart and soul are just little pieces of the Soul of the World. This is in keeping with the pantheism stressed throughout the whole of the book: God is one big soul, the Soul of the World. Because of this, all religions that recognize this fact are one and the same. This is the reasoning behind the ecumenicist thematic of the novel.

This section also contains the climax of the narrative, wherein the magical undercurrent of the novel comes to the fore. In this climax, Santiago talks to the elements: the Desert, the Wind, the Sun and finally the Soul of the World. A few aspects of this scene should be highlighted. First of all, we see that Santiago's communication with these inanimate forces is the realization of the alchemist's assertion that all things, even rocks and animals, have souls. What this essentially does is deny the dualism that we normally assume in our day to day lives: there is no real difference between things and beings. We are all beings with souls, some of whose characteristics are different than others.

Second, it is important to note that while Santiago talks to the Wind, the Desert and the Sun using words, when it comes time to communicate with the Soul of the World he cannot speak. This not to say, however, that he cannot communicate; what it means is that words are not sufficient. Communicating with the Soul of the Word ends up being a matter of opening his heart. This portrayal of language as lacking or insufficient is coherent with other parts of the novel wherein humanity is described as essentially fallen. The problem is not that the secrets of life are complicated, but that mankind has complicated these secrets through the use of language. The final step of Santiago's spiritual journey is therefore not accomplished through speaking, but through listening.

The twist at the story's end - that the treasure was always near Santiago after all - reinforces the teachings of the alchemist. Just as the alchemist insists that the secrets he holds are in fact simple and easy to understand, so too was the treasure always at home. Thus, the secrets to living a happier, more fulfilled life are not far away or exotic: they are quite often right in front of us, right under