The key to solving complex problems is often to find the right abstraction that simplifies the problem without losing its essential features.
图书馆是一个过去、现在和未来相遇的地方。
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.