宏观经济学的核心问题是理解人们如何随时间做出决策。
Every book is a journey, and every journey is a book.
I do not know what I may appear to the world， but to myself I seem to have been only like a boy playing on the sea-shore， and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary， whilst the great ocean of truth lay all undiscovered before me.
下一次绿色革命必须是高产且对环境负责的。