Without the edges, you don't have a middle. Now I think of it though, I remember when the most fun you could have was standing in the middle of a see-saw whils

Without the edges, you don't have a middle. Now I think of it though, I remember when the most fun you could have was standing in the middle of a see-saw whilst your friends sat on the ends.... I don't think it would have been anywhere as much fun if everybody was standing in the middle and there was nobody on the ends to upset the balance.