"Nature is very clear on this. In fact, there’s one fundamental law that all of nature obeys that mankind breaks everyday. Now this is a law that’s evolved over billions of years and the law is this: nothing in nature takes more than it needs. A redwood tree doesn’t take all of the soil’s nutrients, just what it needs to grow. A lion doesn’t kill every gazelle, just one. We have a term for something in the body when it takes more than its share. We call it cancer." - Tom Shadyac in "I Am"