What is the authors purpose of a book?

Books are written for a variety of reasons and the authors "purpose" will more likely then not change from novel to novel.

Some authors write only for the profit/ financial gain.

Others for the fame and recognition.

Some write in the hopes of inspiring others to read.

An excellent example of this would be Eric Walters. A novelist targeting children ages 11+, he was originally a grade 5 teacher- and many of his students HATED to read. Because of this, Mr. Walters, wrote a book that appealed specifically to his students- giving them something to read and enjoy listening to. Since then he has successfully written and published over a dozen novels.

More sophisticated writers may write to try to evoke a deep sense of emotion, universal one-ness, or to evoke thought in the reader.

Catcher in the Rye would be one such book- as one could argue that the author wanted to make people think about sincerity in society VS "phonies" etc.

The purpose of a book, arguably, is to communicate an idea to an audience while allowing for individual interpretation and the use of the imagination.