It gets harder and harder to tell what's real and what isn't in our daily lives. We spend more hours of every day connected to the unreality of events on TV and the internet. This is hardly news, having first been predicted more than half a century ago by the philosopher Marshall McLuhan.
And that's why we think we have a relationship with celebrities. No one is immune. Even the most pragmatic of us has had the experience of seeing a celebrity in real life and started to say "Hello" before we realise we don't actually know that person.
Millions of people, mostly under 30 but not all, spend their days in quasi-relationships with people they admire but don't know on Twitter and Facebook. When the object of their admiration posts something about themselves they respond with comments that will never be seen by the celebrity.
So when someone such as Robin Williams dies, especially in shocking circumstances, we take it personally. It's only normal to regret such an occurrence. After all, the world needs more funny and intelligent people, not fewer. However, we need to keep our perspective and realise that we are not personally bereaved.
Robin Williams was not part of our life. We did not know him. We knew only an image of him. The celebrity reality is famously different from the celebrity image.