The desire to travel prompts Santiago to be a shepherd.
Santiago's purpose is to travel. As a shepherd, he is a nomad. He goes from place to place, and never settles down.
When Santiago was younger, his father told him that only rich people and shepherds were able to travel. The boy decided to become a shepherd.
His father gives him his inheritance early to buy his flock. The boy focuses on his sheep. When he meets a merchant’s daughter, he tells her about his sheep.
"Well, usually I learn more from my sheep than from books," he answered. (1)
The only thing the sheep care about is food and water. They have complete trust in the boy, and have forgotten their own instincts in following his lead.
When Santiago has a dream where a boy leads him to the Egyptian pyramids for treasure, he begins his quest. He meets a fortune teller and an Englishman, and searches for his Personal Legend. It is only once he has reached what he thought was his goal that he realizes that the treasure is where he left it, at home.