I've been at work today, so can't post, but have been thinking about this ...

If you can think of a song a a river...it has a long journey, along which many things will happen to it, perhaps it will broaden, perhaps get channelled in one way or another - it might well get completely polluted, so that no-one wants to drink from it. Tributaries may run into it and add to it - some of it might be evaporated and therefore recycled into other rivers - but at it's source it is as pure as we can find it. And it can have only one source - that being where it came out in the open for the very first time and people realised it was there.