At the beginning he didn't have a clear purpose. As he points out that would be be a problem. After PhotoReading and pulling trigger words he naturally clarified his purpose. As pointed out Paul was there to guide him.
As I do for many in my classes. Your first purpose is not necessarily your final purpose nor are you limited to one purpose for a book.
We ALL know that "to pass the test" is the most immediate goal
No actually that's not the purpose. The why you want to pass the test therein is the purpose. What you hope to be able to do with the information in the future, therein lies the purpose.
If you're not motivated by the immediate goal you need to find your purpose, why are you studying that?
AlexK