People acting in their own self-interest is the fuel for all the discovery, innovation, and prosperity that powers the world.

People acting in their own self-interest is the fuel for all the discovery, innovation, and prosperity that powers the world.

人们为了自己的利益而行动，是推动世界所有发现、创新和繁荣的动力。

-- John Stossel 约翰·斯托塞尔