Basically the sole purpose and aim of economics is to devise way to meet the unlimited and ever growing needs with the limited resources. This has two solutions. Either rise your production which in tern will boost your GDP which will also improve the living standards of the people. Another way is to reduce the demand for luxuries and just consume the basic needs. Since the former does not sounds as impossible as the latter, the world has invented ways to maximize the per capital income and this has given the freedom to consume as much of the depleting natural resources as could be paid for.
I would say that the idea behind our modern economy is to figure out a way to translate a person's effort into a value that can be traded for something else. This is in place of the old bartering system. You have one person with eggs, one person with a cow and one person that can fix wells. If the person that can fix wells needs eggs, but the person that has eggs doesn't need his well fixed, you have a problem. In our economy, the person could fix a well for the guy with the cow for money. Then use the money to buy eggs. Maybe the guy who got money for the eggs would use it to buy milk. This is a very limited example, of course, but that's the general idea. Would you mind telling me what resources you think are actually going to be depleted anytime soon?