The boy noted that there was a sense of fear in the air, even though no one said anything. (2.156)
Just like love, fear is one of the unspoken languages of the desert. Santiago learns to sense it in the air, just like a rabid dog. Er, just like someone who can speak the Universal Language.
"The land was ruined, and I had to find some other way to earn a living. So now I'm a camel driver. But that disaster taught me to understand the word of Allah: people need not fear the unknown if they are capable of achieving what they need and want." (2.152)
When the camel driver lost his property, he was probably tempted to be very frightened of the unknown: How would he pay his bills? How would he feed his children? How would he access Netflix? But the camel driver is a resourceful kind of guy—and someone who's resourceful never has to fear the unknown.
"I want to see the greatness of Allah," the chief said, with respect. "I want to see how a man turns himself into the wind."
But he made a mental note of the two men who had expressed their fear. As soon as the wind stopped, he was going to remove them from their commands, because true men of the desert are not afraid. (2. 657-58)
Santiago's show of turning himself into the wind is pretty terrifying as tents are ripped from their pegs and turbans fly off of people's heads (okay, we made the last part up, but how cool would that be?). Still, the true men of the desert should be accustomed to the desert's power and never show fear. Good luck with that, we say.
He lost his fear, and forgot about his need to go back to the oasis, because, one afternoon, his heart told him that it was happy. (2.509)
Santiago's biggest fear is losing Fatima, and he thinks that if he goes back to the oasis he'll no longer have to feel that fear. But he knows that the Personal Legend is part of his love story, and as his heart gets accustomed to the separation he loses his fear. Plus, video chatting is so good these days, it's practically like being in the same room.
The boy knew the desert sensed his fear.
They both spoke the same language. (2.616-17)
Cue spooky voice: You are becoming onnnnnne with the desert. No, really, this is big: Santiago has learned to observe fear in others, and now he himself is emitting the signs of fear, just like some fear-pheromone that Axe isn't about to stick in a bottle. Nature isn't just a static landscape in The Alchemist; it can actively sense and influence human events.