经济模型的价值在于其解释和预测的能力。

The only way to grow is to challenge yourself.

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.

伟大的真理，其反面同样是伟大的真理。

I'm not a businessman, I'm a business, man.

安全总是过度的，直到它不够为止。