变革在开始时最难，在中间最混乱，在结束时最好。
Change is hardest at the beginning, messiest in the middle, and best at the end.
"The act of writing is an act of optimism. You would not take the trouble to do it if you felt it didn't matter."
I'm a free bitch, baby.
学习数学的唯一方法就是做数学。