Equipped with all our smartphones and cameras, obsessed in social media, we are now facing the challenge that our digital traces are SAVED FOR LIFE in the global network. Human beings are now less able to forget. The danger is that our own memory may against us one day in the future. Say, it can be heart breaking for one to recall sad memories in life, which we may have forgotten in the case without the assistance of external memory. What's more, have you imagined what will happen...