 you crank up the heat because there's a finite amount of trees and you don't know how long you're to live right but imagine if you had a renewable resource imagine if you had solar imagine if you had uh wind right where you knew you can crank the heat up to 75 or 80 in the middle of winter and you're still not using all the power now you can enjoy that energy much more than if you're just using a finite resource so when you're spending principal you're spending a finite resource