There are no permanent trends, only permanent users.
A good mathematician is not one who knows all the answers, but one who asks the right questions.
To imagine is everything, to know is nothing at all.
社会结构的研究是对社会关系系统的研究。
The personality of the teacher is the cornerstone of education.
The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge.
I don’t believe in regrets. I believe in lessons learned.