If you want to understand today, you have to search yesterday.
想要懂得今天，就必须研究昨天。
Don't interfere with anything in the Constitution. That must be maintained, for it is the only safeguard of our liberties. And not to Democrats alone do I make this appeal, but to all who love these great and true principles.
最好的研究往往来自意想不到的观察。
Never look back unless you are planning to go that way.