说话谨慎,行事快捷。
自身无灾无病,感受不到快乐,等到生病卧床,才了解到无灾无病的快乐;家中平安无事,感受不到快乐,等到祸事临头,才体会到平安无事的快乐。
To understand behavior, we must look at its purpose in the context of survival and adaptation.