自然实验是理解现实世界中因果关系的强大工具。
Natural experiments are a powerful tool for understanding causal relationships in the real world.
智慧是对痛苦的理解，对喜悦的感激，以及对过去的接受。
The best solutions often come from listening—to nature, to science, and to the people on the ground.
最好的解决方案往往来自于倾听——倾听自然、倾听科学、倾听实地工作者。