The stranger is close to us, insofar as we feel between him and ourselves common features of a national, social, occupational, or generally human, nature. He is far from us, insofar as these common features extend beyond him or us, and connect us only because they connect a great many people.

学习数学的唯一方法就是做数学。

释义：应当成为秋霜，而不是围栏里的羔羊。