Every smell we perceive is a complex interaction between molecules and receptors, and understanding this interaction is key to understanding our sensory experiences.
The study of complex systems has taught us that simple rules can give rise to incredibly complex behavior.
攻击我很厉害我也回敬得很厉害,攻击我很轻微我也回敬得很轻微。 
The goal of software engineering is to control complexity, not to create it.