What does the title, "Soundness of Mind and Freedom of Will" refer to?

Just as Turtle closed a chapter in her life by reenacting the burial of her mother, Esperanza finds relief in the ceremony of giving up Turtle. Esperanza never got a chance to say goodbye to her daughter, Ismene, so she finds closure in a formal goodbye scene with a girl who looks like her own child and whom she loves like her own child. She also has the comforting illusion that she has left her own daughter in good hands with Taylor, a relief because she does not know who now cares for Ismene. The goodbye serves as a catharsis, a purification leading to renewal. Taylor notices that Esperanza’s face looks refreshed as she leaves the office. As Taylor later tells Estevan, “[S]he seems . . . as happy as if she’d really found a place to leave Ismene behind.”