Why do Creative People Create?

I read an article the other day talking about something called the "creative flow state". Apparently some neuroscientists think that this experience might be one of the most addictive experiences possible. I don't know if that is completely true, but as a writer I can attest to the thrill of the "flow state". If you haven't ever experienced it, it is hard to describe. For me, the words flow down to the page almost by themselves, as if I'm watching a living thing grow all on its own. It's an incredible feeling and makes the periods of writer's block all the more agonizing. As difficult and painful as writer's block can be, the anticipation of the next "flow state" makes the wait worth it. Actually, I'm sitting at my kitchen table right now, wishing that the flow state would make an appearance. It will eventually I guess. It's the reason I keep going even when it feels like I can't put a coherent sentence together.