Coelho's book, The Alchemist, is very much centered on one's perceptions and one's choices. He denounces the idea of "fate" by telling the boy that he can choose to make his own future by searching out his Personal Legend. If one perceives that he cannot succeed, Melchizedek notes that this will keep him (or her) from realizing his (or her) dreams. In fact, Melchizedek tells Santiago that this is something he (the old man, the King of Salem) does: he comes to people when they are about to give up, when they are only a breath away from achieving their heart's desire. He explains about the world's biggest lie, a dangerous stumbling block for every individual:
“Everyone believes the world's greatest lie..." says the mysterious old man.
"What is the world's greatest lie?" the little boy asks.
The old man replies, "It's this: that at a certain point in our lives, we lose control of what's happening to us, and our lives become controlled by fate. That's the world's greatest lie.”
Fate is the concept that our lives are pre-determined for us, and out of our control...that whatever we do, our fate is already sealed, and whatever we do will not change it. Melchizedek says this is the lie. For once we believe this, we lose control of making choices and finding what will make us happy in life. For Santiago, he discovers it's not the treasure that is truly valuable, but realizing what treasure really is: Fatima, love.