一个好的数学问题的定义是它产生的数学,而不是问题本身。
The definition of a good mathematical problem is the mathematics it generates rather than the problem itself.
The boundaries which divide Life from Death are at best shadowy and vague. Who shall say where the one ends, and where the other begins?
Development economics is ultimately about improving people's lives.
"The most powerful tool we have as leaders is our own example."