On Facebook, one reader said that he doesn't believe in controlling emotions, because humans are sad by nature. I suppose considering that we’re all doomed to die, we have good reasons to be sad, if you think about it. Thinking about it, however, doesn't need to involve an emotional response. And the fact that our lives end is a fact, an emotionally neutral fact. Interpreting this fact through sadness, I believe is a cultural phenomenon. But I don’t like abstract philosophical concepts, and practically speaking, none of our emotions is perfect. These imperfections are implemented in each emotion by design, and their purpose is to create a pathway through which you can change your mind. For example, imagine that you wish to buy a car. Let's suppose you really want one particular model, and thinking about it excites you, makes you happy. But then you discover something about that car’s flaws, and you no longer want it. You no longer feel joy when you’re thinking about it. Note that there’s nothing about the car that would suggest an emotional response. The emotion that you’d experience is entirely internally generated in your mind. In order for such a shift in emotions to take place, your mind turns off the joy that it had attached to the idea of the car and replaced it with a new one. Your mind can turn off an emotion because any emotion always contains defects, which your mind uses to turn your emotions off. These defects also allow you to turn off any emotion that bothers you, either temporarily or, with many repetitions, permanently.