This comes near the end of Chapter Cinco. Tony overhears his uncle and mother talking as he is falling asleep. His uncle says there is hope in Tony because he has the characteristics of the Luna family, whereas his other brothers are more like the Marezes. There is a story passed among the Luna generations that a priest will return and guide them to salvation and good harvest. Both Tony's mother and his uncle hope he will become that priest, but his uncle says that Tony must stay with the Lunas after his first communion, so that he will not be lost like his brothers.
Throughout the novel, Tony is torn between the world of his father and the world of his mother. They represent both halves of his soul, & they are in constant conflict with each other, creating the inner turmoil Tony must learn to calm in order to mature. He needs to reconcile these two halves in order to be whole. This is where Ultima comes in. She guides him to understanding of his true self, and allows him to express his true nature in his life.