How does the boy's name of Santiago relate to the abandoned church and the upcoming story, where the boy goes on a journey seeking a treasure ?

The story opens with the main character, the shepherd Santiago, arriving at an abandoned church with a sycamore growing in it in the Spanish region of Andalusia. He decides to stay the night at the church and corrals his herd into the church grounds. He falls asleep using the book that he keeps with him at all times as his pillow. During the night, he has a dream that he has had several times before, a dream he has never been able to fully understand. While waking his herd, he realizes that he is very close to the animals; they operate on the same schedule and he calls them all by name, convinced that they understand his conversation with them. They are very simple creatures, though, wanting only food and water. Recently all of this thoughts and conversations with the sheep have been about a girl he met a year ago, at the town that is his next destination. She is the daughter of a merchant and he has been thinking about her ever since he left.