Just consider his poem "Thoughts on Study": "A small pond, yet its waters glint like a mirror / How can the water, which sits in one place, remain so clear? / Because there is always fresh water flowing in." This poem is a metaphor for Zhu's belief that one should never stop reading, because a person could learn something new each time he opened a book.
而他的詩〈觀書有感〉：「半畝方塘一鑑開，天光雲影共徘徊，問渠那得清如許，為有源頭活水來。」是他自覺每次讀書總有新覺悟，如有源頭活水來也不窮所做。