When you start learning a topic you become a BEGINNER.
When you start acquiring knowledge in a chapter you become a LEARNER.
When you start thinking deeply in a chapter, you become a THINKER.
When you become very knowledgeable in a chapter, you become an EXPERT.
When you become a specialist in a chapter, you become a SCHOLAR. When you reach this level you can be assured that you have gained the best possible knowledge in a chapter.