你和我各有一个苹果，如果我们交换苹果的话，我们还是只有一个苹果。但当你和我各有一个想法，我们交换想法的话，我们就都有两个想法了。
You know, in the Middle Ages, in England, when you met a very poor person, that person would be described as an "unfortunate" -- literally, somebody who had not been blessed by fortune, an unfortunate.
The best way to be loved is to love.
密码学的目标是使破解系统的成本超过受保护信息的价值。