1. If you don't peck at jade, you won't spoil it; People don't learn and don't know. -Book of Rites

2. Black hair doesn't know how to study early, and white hair regrets studying late. -Yan Zhenqing

3. There are not many students who study, but as the meaning suggests, they are unknown; Don't learn if you are suffering from it, but you can't learn if you are suffering from it. -famous sayings (Tang) Han Yu

4. Those who study without doubt must be taught to have doubts, and those who have doubts must have no doubts. Only here can they make progress. Chu Hsi