The purpose of identifying an author's purpose is to help the reader understand what really motivates different writers to write. In order to do so, students must start by questioning the purpose of the text, discussing its structure, realizing how the text made them feel, making connections to their own writing and observing as the purpose changes over the course of the text.
To begin understanding the writer's true motivations, students of literature must ask themselves why they think the author wrote the book, possibly comparing his purpose to the purpose of different editorials or advertisements. The next step is to understand how the structure of the text helps reinforce the author's point. Such structures include problem-and-solution scenarios and cause-and-effect scenarios within the text that can help explain some of the plot events and put those events into perspective for the reader.
After finishing the text, the reader should ask himself how the text made him feel. This gives him a chance to review and understand the steps the author took to make him feel this way. Readers should also look to their own writing and how they communicate their ideas according to their own purposes in order to better understand how the author communicates his. Finally, readers should pay attention to the different purposes that may exist within the text. Any text may have multiple purposes, and identifying how and why these purposes shift helps the reader understand the motivations of the author.