It sure seems to be a concept people are reluctant to grasp. When I read an article about how we will feed 12 billion I just want to ask why? And if we manage to feed 12 billion, what about 18 billion. Is their no limit. It's not as if the Earth is getting bigger. We are on the down hill slope of cheap fossil fuel energy, a resource deposited once ages ago and never to be replenished in the scale of human life on Earth.