What is the theme in By the River Piedra I Sat Down and Wept by Paulo Coelho?

One of the main themes in the book is that of letting go of "the Other," which is a negative voice in a person's head that makes them question their desires and ambitions and compare them to what society considers acceptable. Pilar is a deeply-conflicted person and is constantly being controlled by the Other. Her friend gives her an exercise to do in order to rid herself of the societal and religious hampers and burdens that control her life. The exercise teaches her to be aware of when the Other is trying to control her by questioning every action that she makes and comparing it to the action that the person she wants to be would have made