Natural experiments can provide valuable insights into economic questions.

Every child should have mud pies, grasshoppers, water bugs, tadpoles, frogs, mud turtles, elderberries, wild strawberries, acorns, chestnuts, trees to climb, brooks to wade in, water lilies, woodchucks, bats, bees, butterflies, various animals to pet, hayfields, pine-cones, rocks to roll, sand, snakes, huckleberries and hornets; and any child who has been deprived of these has been deprived of the best part of education.

最有力的时刻是无言的时刻。

Never stop learning, because the world never stops changing.

Research is not just about answering questions but also about asking the right ones.

互联网竞争就像冲浪，错过一波就永远错过了。

艺术源于必要性，而非时尚。