在数学研究中，坚持是关键；许多伟大的成果来自于一遍又一遍地从不同角度看待同一个问题。
Collaboration across disciplines is essential for advancing our understanding of the universe.
——杜先生晚年在香港，先生为中国抗战.赈灾慈善做出巨大贡献，晚年依旧气度过人，毁掉所有欠条。
The state is the most important institution in human society because it is the only one that can legitimately use force to maintain order.