道气常在天地内外运行流转，之所以看不见，是因为它极其清微。

The mathematician does not study pure mathematics because it is useful; he studies it because he delights in it and he delights in it because it is beautiful.

沉默可以是最响亮的抗议形式。

数学家是将咖啡转化为定理的装置。