Personal Legend
The book's central idea is that every person has a specific purpose they were born to pursue. Characters who chase theirs grow. Characters who abandon it, like the crystal merchant, stagnate. The whole plot tests whether Santiago will keep going when it gets hard.
Fear versus action
Fear stops more characters than any external obstacle does. The crystal merchant, the Englishman, and Santiago himself all face moments where stopping feels safer. The book consistently shows that the cost of stopping is higher than the cost of failing.
Reading the world as a language
Santiago learns to treat everything around him as information: hawk fights, strangers, sandstorms, and coincidences all carry meaning. The book treats attention as a skill that can be developed, and shows Santiago getting better at it over time.
The cost of comfort
Every time Santiago finds stability, something forces him to leave it. The crystal shop is comfortable. The oasis with Fatima is comfortable. The book treats comfort as a slow trap, not a reward, and the alchemist makes this explicit when he pushes Santiago to keep moving.
The journey as education
Santiago does not arrive at the pyramids as the same person who left Andalusia. Each stage of the trip teaches him something he could not have learned at home. The book argues that the transformation matters more than the destination.