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。
The probability of a response is determined by its reinforcement history.
"A story is a gift that keeps on giving."
War is peace. Freedom is slavery. Ignorance is strength.