After reaffirming his love to Fatima, Santiago sets across the desert with the alchemist. They travel in silence, eating the game that the alchemist's falcon brings them. Santiago grows restless, is hungry for more of the alchemist's secrets. The alchemist explains that Santiago has learned much, but the one thing that he has left to learn cannot be taught. He must learn it for himself. In the beginning, the alchemist explains, the secrets of the universe were known to all, but men have been complicating things because they seek the treasure of their Personal Legends, but do not with to live their Personal Legends. The alchemist advises Santiago to listen to his heart.
The two travel cautiously now, because they are nearing the area with the most warring tribes. Santiago listens to his heart and finds it agitated. It begins to tell him stories about the Soul of the World - about others who have failed to find their fortune. It is scared and wants to go back to Fatima. Santiago tells the alchemist that his heart is treasonous, that it does not want him to continue. "Treason is a blow that comes unexpectedly," comes the reply. "If you know your heart well, it will never be able to do that to you." (129)
As they travel, Santiago listens to his heart and eventually comes to be at peace with it. As the journey nears its end, Santiago tells the alchemist that he wants to know some secrets of alchemy. The alchemist tells Santiago that he already knows many important secrets; he knows that one must listen to the Soul of the World to find one's treasure. Every thing on earth, even minerals, has a Personal Legend. This is why alchemists can change any metal into gold: they are simply helping the metal achieve its Personal Legend.
The war finally catches up with the travelers and they are taken captive by a warring tribe. The tribesmen take them for spies and threaten to kill them. To save his and Santiago's lives, the alchemist gives the tribesmen all of Santiago's money and tells the tribesman that Santiago is a powerful wizard who can turn himself into the wind and destroy them. The tribesman don't believe him, but give Santiago three days to prove himself.
Santiago panics because he has no idea how to turn himself into the wind. The alchemist seems unconcerned. For three days, Santiago goes up on a cliff and contemplates the desert, listening to his heart. Finally, on the third day, he goes to the very top of the cliff and uses his heart to talk to the Desert - since they both speak the Language of the World. He asks the Desert to help him turn himself into the Wind, because he is love with a girl and wants desperately to go back to her, but the Desert does not know how. Next he asks the Wind, but the Wind does not know what love is. Finally he asks the Sun, who knows what love is, but cannot help Santiago. The Sun suggests that Santiago ask the Hand that wrote all. Santiago then starts to pray - but that prayer emerges as not a request but an acknowledgement, as if culled from some deeper knowledge, that his heart and the Soul of the World are the same thing. Once Santiago comes to this realization, the wind begins to furiously blow and the tribesman find that Santiago has disappeared. He reappears on the other side of the camp. The tribal chiefs are so impressed that they let the travelers go and give them a guide so that they can reach their destination safely.
The next day, the alchemist and Santiago arrive at a coptic monastery. The alchemist uses his piece of the Philosopher's Stone to turn lead into a quantity of gold and gives some to Santiago and some to a monk. (He also gives an extra piece for the monk to hold onto for Santiago in case something should happen.) The alchemist takes his leave of Santiago, who travels farther and finally comes to the Pyramids. There he is overwhelmed with joy; he realizes all at once that he can turn back now, that the real treasure is not gold or jewels but the wisdom he has gained and his love for Fatima.
The alchemist told him, however, to listen to his heart. His heart tells him to start digging in the spot where he sees a scarab beetle. As he starts digging, a group of men approach him and beat him savagely, taking all of his money. When Santiago tries to explain what he is doing, one of the men tells him that he is a fool. He goes on to explain to Santiago that he had a recurring dream, too, depicting the same situation - but in Spain instead. He, however, was not stupid enough to go chasing after it, he remarks. After the robbers leave, Santiago gets up, elated. He now knows where his treasure lies.
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 our noses. The rub is that often we must travel far and wide in order to realize this.