A friend of mine was telling me about one of those odd relationship idiosyncrasies that she had with her boyfriend. It was one of those pet phrases things that only really make sense to the two of you.

And then she said to me that she was amazed by how it didn't matter how many people you meet that always seem unique.

Now that's something that doesn't amaze me. I've always been told everybody in the world have only one thing in common and that is that they are unique. Or however the cliché now.

But the point, as she explained it, was interesting. She was talking about the moment that people stop being in our memory in relation of somebody else. So they stop being "Steve, you know friend of Dave's" and become just "Steve". And the reason for this stuff usually is that you've discovered something about them that to continue with the example, distinguishes them from other "friends of Dave".

It is in this way that we define the people we refer to as "our friends" rather than people we "are friendly with".