To travel is to write with your feet.

If a Nation expects to be ignorant and free in a state of civilization,it expects what never was and never will be....If we are to guard against ignorance and remain free,it is the responsibility of every American to be informed."

过去是一个异国；他们在那里的做法不同。

矩阵力学是对经典物理学的彻底背离，但它是解释原子世界所必需的。