1931年9月,钱穆北上,任北京大学历史系副教授,讲授中国上古史。当时,北京大学有自由讲学的传统,教师讲课不一定按学校课程所规定的内容讲授,只要你见解深刻,言之成理,也会得到学生的欢迎。钱穆浸润先秦诸子十余年,以《纪年》订《史记》之误,多有心得,他讲的战国史别具一格。 In 1931 September, Qian Mu northward, Ren Peking University associate professor of history, teaching Chinese ancient history. At that time, Peking University had a tradition of free lectures. Teachers’ lectures were not necessarily taught according to the content prescribed in the school curriculum. Students should be welcomed as long as you have profound insight and truth. Qian Mu infiltrated the pre-Qin philosophers for more than ten years and set “Historical Records” in his “Annals of the Year of the Chronicles” as many mistakes and experiences as he wrote about the history of the Warring States Period.