Here's a situation to teach you economics: image you have your keys locked in your car. A locksmith is likely to charge you a lot of money for his services. If he charges too much however you will sooner break your car window than pay him a ridiculous amount of money. Breaking your window would be a substitute for the locksmith's services. Substitutes are made when the cost of something is too high. So when do you think we will have a substitute for the gasoline powered engine? Now that you read Capitalism's Truths you know that will happen whenever gasoline gets high enough that folks aren't willing to pay for it!