Thanks for translating. Thought someone might have a shot at answering this by now.
Purpose is what you hope to gain from doing something. Whether it is reading, getting up in the morning, writing a letter. Why are you doing it?
Why are you reading this book? What do you hope to know, use, get better at as a result of reading this book?
Finish the sentence "I am reading this book so that I can..."
... find peace in my life
... learn something I don't know about...
... start solving this relationship problem.
... have more free time from studying because I understand this subject better.
When it comes to reading you really need to think about the book in terms of "What's in it for me?" What do I want out of it?
Alex
