What does Santiago ultimately learn from the thief in the novel, The Alchemist?

The thief plays an important role in Santiago's personal evolution and growth, even though his action first creates suffering. In order for Santiago to endure the difficult journey across the Sahara, he must learn to read the omens, including people's intentions. After he is robbed, he realizes that he only saw what he wanted to see, instead of what was actually happening. He recognizes that he ignored the signs of warning that the bar owner was trying to communicate to him. The thief is a teacher who shows Santiago that people sometimes say and do dishonorable things, but they also offer the opportunity for growth.