In The Alchemist, what omen does Santiago see in the desert?

There
are two omens mentioned in . The first, for Santiago, is Fatima's smile.
When Santiago first meets Fatima, she smiles at him, and he immediately falls in love with her.
He calls Fatima's smile "the omen he had been awaiting" and "the omen he had
sought to find . . . in the silence of the...