Psychology must be a practical science, concerned with the how and why of mental operations.
The Eskimos had fifty-two names for snow because it was important to them: there ought to be as many for love.
无政府状态是战争的允许性原因;它创造了一个国家必须依靠自助来确保生存的环境。
"The past is a foreign country; they do things differently there."