你必须愿意牺牲才能得到你想要的或你需要的。
You have to be willing to sacrifice to get what you want or what you need.
The right of a nation to kill a tyrant in case of necessity can never be doubted until the right of a tyrant to kill a nation has been proved.
If you can dream it, you can achieve it.
Every mathematical problem is a puzzle waiting to be solved, and every solution is a step towards greater understanding.