冯友兰在《我在北大当学生的时候》中描述到:“那个时候的北大,是一个‘自由王国’。蔡元培到北大以后,开课并不是先有一个预订的表,然后拉着教师去讲,而是让教师说出他们的研究题目,把这个题目作为一门课。对于教师说,功课表真是活了。他所教的课,就是他的研究题目,他可以随时把他研究的 Feng Youlan described in ”When I was a Student at Peking University:“ ”Peking University at that time was a ’free kingdoms’." After Cai Yuanpei went to Peking University, it was not the first time that a booking was made for the commencement of classes, , But let the teacher say their research topic, the subject as a lesson to the teacher that the homework table is really alive.He taught the class, is his research topic, he can at any time to his research