The phrase in question functions as a proper noun, specifically a title referencing a biographical or fictional work. It denotes a book centered on an individual named Peter, identifying him as the primary subject.
Such a work can serve various purposes, including documenting a life, exploring themes of faith, leadership, or personal transformation, and offering insights into a specific historical period or social context. The narrative structure allows for detailed examination of character development, key events, and the subject’s impact on others.