So each one, just a few minutes, we're going to kind of go over the big idea and then give you some examples of the history and see if that can't hook you up with a better grade. So let me go find a traditional economic system and giddy up, we'll get going. So traditional economic systems are based basically around agriculture and the barter system. So we don't have cash and we don't have banks yet, so basically kind of an individual kind of farming idea where people are self-sufficient to a certain degree in their communities. So there's not a lot of trade going on, but maybe bartering. So I give you food and maybe you give me chickens. Well, that is food.