Jianing: Hi Juan, I think you have made a really good point here. And I would like to add another point in accordance with yours, which is to make the picture more fully revealed for others who may read your piece. You have made it clear why people should worry about metadata collection when the actual content is not being overheard; but I believe there are still people in the world who don't even understand why privacy matters. It may be in their interest to watch the TED Talk delivered by Glenn Greenwald. Basically,Greenwald has made three arguments on the importance of personal privacy: First, those who claim that privacy is not important never fail to protect their own privacy while pointing their fingers at others; secondly, as far as mass surveillance is concerned, those in power are not simply looking for criminals, but whoever with the ability to pose a threat to their power, and the overall freedom of a society is measured by how it treats its dissidents, not its obedient citizens; thirdly, a private place is what human creativity needs to be activated and empirical studies have shown that human behaviour become dramatically more conformative when people know that they may be overseen at any time.