The purpose of a model is to be simple enough to understand and use, but complex enough to capture the essential features of the system.
模型的目的是足够简单以便理解和使用，但又足够复杂以捕捉系统的基本特征。
半夜三更所想的事与清晨八时所想的事情太不一样。
The poet is a man who manages to be, in his own lifetime, what all men would like to be after their death.