Mathematics is a conversation between the past and the future.

Though love seems the fastest of all growths, it is really the slowest. No man or woman knows what perfect love is, until they have been married a quarter of a century.

The Soviet Union was a civilization of fear, where people lived in constant dread of the knock on the door at night.

人生最大的美德是真正的勇气，懂得如何面对事实并超越它们。