Why one writes is a question I can answer easily, having so often asked it of myself. I believe one writes because one has to create a world in which one can live. I could not live in any of the worlds offered to me -- the world of my parents, the world of war, the world of politics. I had to create a world of my own, like a climate, a country, an atmosphere in which I could breathe, reign, and recreate myself when destroyed by living. That, I believe, is the reason for every work of art.
-- Anais Nin, 'The New Woman', Ramparts June 1974

And if you can find the whole essay someplace (I couldn't find it online), it's definitely worth a read for that wonderful, emboldening call-to-arms that Nin is capable of.

Also, I wasn't sure 'emboldening' was a real word, but the spellcheck has allowed it, so I figure I'm gonna run with that!