If you're not stubborn， you'll give up on experiments too soon. And if you're not flexible， you'll pound your head against the wall and you won't see a different solution to a problem you're trying to solve.

逝者从未远离我们，他们在我们心中，在我们脑海里，永远如此。

自守形式的研究证明了对称性在数学中的力量。

"A book is a conversation with the dead."