Where does civilization stop and wilderness begin? What is natural and what is artificial? If all things are made of protons electrons and neutrons, then what is the difference between natural and artificial. Humans build things. We call those things artificial. Things that are not built by humans we call natural. What about a beaver dam. It was built. Is smog natural? It changes the make up of the atmosphere and makes it more difficult for mammals to breathe. But the natural world is made of things that can kill humans, such as snake venom, spideer poison, certain kinds of mushrooms and plants. Seventy percent of the world is covered with water that humans cannot drink. Yet the world is teaming with life. We depend on living things for our food and often our shelter. Even petroleum comes from living things. We still haven’t figured out how to create life. We can only manipulate that which is already alive.