Santiago is a sheep herder and had a dream about a personal legend that he wanted to pursue because he was so intrigued by this "Personal legend.
Santiago decided to seek entail about things like dreams and tells a physic about his experience and all she says is to go with what his souls speaks.
After being let down ny the very vague response he decides to not go after his "Personal Legend" and instead buys a book, Santiago encounters a "King" and developed a bond with him and he is considered to go after his personal legend again.
He meets an Alchemist not realizing that is his soul purpose is to become an alchemist. After his encounter with the alchemist he has been intrigued to where he doesn't think that he should not bet looking anymore.
He has finally come the conclusion that his very soul purpose is to become an alchemist its and he soon realized that it was the personal legend that he was dreaming about.
He is now going around the world that he always wanted to do when he was younger and now decided to be a full time alchemist and knowing that this was his dream.