From another point of view, humans and nature can be said to be in conflict. Nature is often seen by humans as natural resources. People cut down trees, mine ores, and grow crops. Fires, cars, and factories make a lot of smoke and harm many places. People who like to leave nature unharmed and those who feel they need to use more of nature often fight about what they should do. In the modern world, with many more people and many big cities, these problems are becoming more serious.