When Santiago and the alchemist are taken prisoner by a hostile tribe, the alchemist barters for their release and uses as leverage the opportunity to see Santiago turn himself into the wind. Santiago then listens to his heart, which allows him to speak to the desert, the wind, and the sun, as he tries to learn how to transform himself. Santiago speaks to the desert about love, and the desert offers its sands to help the wind blow, but it cannot transform Santiago into the wind.
The timeline below shows where the character The Desert appears in The Alchemist. The colored dots and icons indicate which themes are associated with that appearance.
...everyone that when improvement is sought, everything becomes better, and love is the transformative force. The desert is static, the wind is always moving, and the sun sees everything from a remove.... (full context)