Once upon a time...

...there was a big, dark cloud. It was good at hiding, and so would only come out when the mood was particularly blue. It followed the blueness around for a while before it rained a little, and then disappeared. But one day, not long ago, the cloud got bigger and bigger and the mood bluer and bluer. It caused a thunderstorm every now and again, and each time the grey cloud got bigger and bigger and blacker and blacker until it completely blocked out all the sunshine for the little person just underneath it. And the rain came and there was no sun to dry it out and cast light; the life underneath the cloud is waterlogged and dark and wishing the cloud would move along on its way sometime soon.