Dust is not a constant. There’s not a fixed quantity that has always been the same. Conscious beings make Dust—they renew it all the time, by thinking and feeling and reflecting, by gaining wisdom and passing it on. And if you help everyone else in your worlds to do that, by helping them to learn and understand about themselves and each other and the way everything works, and by showing them how to be kind instead of cruel, and patient instead of hasty, and cheerful instead of surly, and above all how to keep their minds open and free and curious… Then they will renew enough to replace what is lost through one window. So there could be one left open.