数学之美不仅在于其抽象的优雅，还在于其建模和解决现实世界问题的深刻能力。
However difficult life may seem, there is always something you can do and succeed at.
"We are all of us made by what we have lost as much as what we have gained."
"Every discovery in science is a step closer to understanding our place in the cosmos."
打开纠缠在一起的绳结的最好方法，不是要去「解开」绳结，而是要不断地把松动的部分拉得更宽。尽可能把那团乱麻弄大、弄松、弄开。当你打开绳结的时候，它们就会自行解开。这招适用于绳索、线、软管、毛线或者电线。
The best way to untangle a knotty tangle is not to “untie” the knots， but to keep pulling the loops apart wider and wider. Just make the mess as big， loose and open as possible. As you open up the knots they will unravel themselves. Works on cords， strings， hoses， yarns， or electronic cables.