A gentleman has Jiu Si: he thinks clearly, listens attentively, looks gentle, looks respectful, speaks loyally, respects the temple, doubts and asks questions, and resents the difficulties, as it seems-Confucius
asking a question is often more important than solving a problem-Einstein
doubts. Always doubting, not judging, that's the shortcoming-Lu Xun
Example: Zu Chongzhi showed a keen interest in mathematics and astronomy since he was a child. He "specialized in mathematics and refined ancient and modern times", but he never "falsely extrapolated the ancients" and never bound himself to ancient books and predecessors' theories. He dared to doubt the stale theories of his predecessors, to overthrow their erroneous theories, and to critically accept their scientific heritage. In his youth, he made a careful study of the academic achievements of Zhang Heng, Zheng Xuan and others, corrected some mistakes and made many valuable research achievements. Later, he found that there were many mistakes in the "calendar" compiled by the famous astronomer He Chengtian for the Song Dynasty at that time, so he began to rewrite a new calendar-Daming Calendar.