How does the boy and the alchemist find food in the desert?

Actually, it was a little more than catching a snake. It wss the process, the advice, and the memory of what he'd learned. You couldn't catch the snake unless you seen the bird.

"Yes, the old man had known what he was talking about: during the time the boy had spent in the fields of Andalusia, he had become used to learning which path he should take by observing the ground and the sky. He had discovered that the presence of a certain bird meant that a snake was nearby, and that a

certain shrub was a sign that there was water in the area. The sheep had taught him that."