Dreams (Sleeping)
It is a dream that first leads Santiago to pursue his destiny. It is also a dream (although someone else's dream) that sends him back.
Santiago dreams of a child showing him a treasure at the base of the Pyramids; when we first read of the dream, we are led to believe that Santiago has had it before. When he tells the gypsy of Tarifa and Melchizedek about this dream, they both implore him to follow it, because, they argue, dreams are the language in which the Universe speaks. At the end of the book, it is the dream of the robber–which was the exact inverse of Santiago's dream, showing the treasure at the abandoned church–that sends Santiago back to Spain and to the treasure. The theme of dreams is linked, then, with the theme of fate, since dreams are the way in which people come to know their destiny.
Love
When the story of The Alchemist begins, the reader finds Santiago looking forward to a rendezvous with a merchant's daughter he met the previous year. As soon as he is convinced to go in search of his treasure, however, Santiago forgets all about the girl. Then he meets Fatima at the Al-Fayoum oasis, and thinks about giving up his quest to be with her. The difference between the two cases is two-fold.
First, what Santiago felt for the merchant girl was not love. It was merely an attraction that had no spiritual element to it. For this reason it was very easy for Santiago to shrug her off and continue with his fate. In the case of Fatima, though, everything is different. The first time that Santiago and Fatima see one another, Santiago feels that the Soul of the World is speaking directly to him. Secondly, Fatima does not encourage Santiago to abandon his Personal Legend. It is for this reason that Fatima's love does not prevent him from pursuing his fate. Since Fatima is part of Santiago's fate, she does not stand in the way of his Personal Legend. This is the fundamental difference between true love and all other love and one of the main themes of The Alchemist - namely, that true love never gets in the way of living one's life to the fullest. If one has to choose between a Personal Legend and love then that love is not true love after all.
Fate
One of the fundamental themes of The Alchemist is that our paths are pre-ordained or maktub, in the words of the shopkeeper. The goal of life is to live in harmony with what is ordained for one, or one's Personal Legend; happiness depends upon this harmony. Ostensibly, we all once knew, as children, what our Personal Legends were. The main problem is that as humans and adults, we strive to make things more complex than they really are. In the text of The Alchemist, this problem is mirrored by the experience Santiago has with alchemy. While traveling through the desert with the Englishman, Santiago reads several books about the secrets of alchemy. The books claim that the original secret of alchemy could be written in a single sentence, but that mankind had made its explanations of that secret so convoluted that they could not be understood by anyone. Santiago rejects this and contends that he can learn everything he needs to know about alchemy through his day-to-day life. This conviction, that one's fate, or Personal Legend, is apparent in any aspect of one's normal life forms one of the most important themes of The Alchemist. When Melchizedek says, "When you want something, all the universe is conspiring to help you achieve it," (22) he means that since it is fate that puts a desire in Santiago's heart, fate won't stop him from achieving it. The problem is focusing one's energy on determining what it is that one really wants. Santiago does this during the last leg of his journey with the Alchemist, when he learns from the desert to look inside himself and silence his petty fears. By silencing these fears, he is able to finally see that he is one with the world around him and that his Personal Legend is a harmonious part of that world. This is evinced in a magical fashion when Santiago is able to communicate with the elements, in the climactic scene in which he turns himself into the wind.
Unity
The unity of all existence can be traced as a theme through two main aspects of the narrative. First, as Coelho describes it, the Soul of the World unites us all - people, plants, rocks and elements. Second, that there is no significant difference between the different religions of the world. In the narrative of The Alchemist, this unity of humans and the natural world is pointed out several times. One example is the Alchemist's assertion that even material elements have a Personal Legend. The reason that alchemists can turn any metal into gold is because it is the Personal Legend of that common metal to become gold. Alchemists help elements achieve their Personal Legends in much the same way as the Alchemist helps Santiago realize his own Legend. This unity with the natural world can also be seen when Santiago converses with the wind, the desert and, finally, the one hand which wrote everything. This, the reader is to understand, is God.
In a sense, the final realization of the book is that Santiago's soul is just a part of the Soul of the World, which is the same as God. This in turn translates in to a much more pragmatic ecumenicist theme in the book - that is to say, that throughout the narrative there is a minimization of the difference between Muslim and Christian, the two religious spheres in which the narrative takes place. The reader is led to understand that since God is one with all of creation, all religions are essentially saying the same thing. Thus, Santiago's initial thoughts about the strangeness of the "infidels," as he first refers to the residents of the city of Tangiers, are quite quickly swept away by his realization that the spiritual concerns of Muslims are very similar to his own. The shopkeeper's concerns about his dream of pilgrimage to Mecca can be identified with any dream that one is afraid of fulfilling.
Selfishness
The book opens with a prologue which retells the story of Narcissus, bringing the question of selfishness to the fore. In the traditional telling of the story of Narcissus, Narcissus drowns in a lake because he is so enamored with his own reflection that he falls in. In the prologue's unique retelling, it is revealed that while Narcissus was selfish, the lake in which Narcissus drowned was also selfish. After Narcissus' death, the lake misses him because it could contemplate itself in his eyes. This already tells the reader that the theme of selfishness will not be treated in a one-sided, moralizing manner.
Selfishness reappears in the form of the Personal Legend. The Personal Legend is something which a person truly desires with all of his/her heart. The novel suggests that the only thing that is important in life is to pursue this dream at whatever cost. Often this means avoiding things which are not conducive to achieving this dream. In the case of Santiago, this means leaving his familial home. It also means that any love which he experiences must not get in the way of his Personal Legend.
The novel states that, since the Personal Legend is placed in one's heart by Fate or the Soul of the World, pursuing the Personal Legend is not an option; it is instead one's duty. The Alchemist thus suggests that selfishness is not necessarily evil, but is to a degree the only way to live at peace with the universe and to be happy.
Dreams (Aspirations)
Dreams in the sense of "goals" or "aspirations" also constitute a major theme. Santiago's dream of the treasure provides him with a goal; Santiago resolves to find the treasure, and by his decision to pursue this goal he is able to realize his Personal Legend. Thus, Coelho plays with the dual (and of course linked) meanings of the word "dream", as both visions during slumber and far-reaching objectives. In this sense, the message of The Alchemist could be described as follows: everyone needs a dream. The vulnerable periods of Santiago's journey are when he has no clearly defined goal. This is true when he finishes working at the crystal shop, as well as when he contemplates staying at the oasis with Fatima. Both times he thinks about desisting, but winds up carrying on unswayed.
As a counterpoint, we can think of the shopkeeper, who is afraid to realize his dream of going to Mecca. He does not want to achieve his dream because he feels that it is the only thing keeping him looking forward to the future. Santiago tries to show him that if it is his destiny, he has no choice but to seek it out, or else he is not living. In this way, The Alchemist is not about what one should dream, but merely that one should dream.