What runs but never walks, falls but also climbs, takes the shape of what contains it and can contain a thousand shapes but has none of its own. Light can give it colour though it often has none of its own and it travels around the word daily saving and killing at the same time. People die for it, from it or in want of it, some with too much some with not enough some store it up so take it away some live by it day by day. What is it?