Well it turns out that there are two kinds of problems that you have to worry in any regime of property rights. One of them is the question that one person will take this property right and use it to blockade the way in which others can use things of their own. Now what legal systems instinctively knew, is that if you allow a blockade, it's not going to encourage productive use of a resource. What it's going to do is to allow one individual to make sure that somebody else doesn't have access to that resource unless it turns out that they buy their way in. You then have to figure out who is going to be the person whose got that dominant whip hand; and you have to ask yourself whether or not if there are millions of people out there, you can enter into bargains with all of them, so as to get rid of the appropriate blockade. The second problem is the externality problem. That's a problem which says I'm using whatever it is that I own. What I am going to do is essentially now create noise or filth of one kind or another that spills over quite literally into somebody else's land, and if it turns out that you don't have private property, you don't have the externality problem. And so what you're constantly trying to worry about is which of these two problems is bigger. And what you do is you now have a river, and what it does is it runs a very long period of time and there are many people who are riparians that own property on either side of the river. Well, if I can bottle it up, it means that no downstream user can essentially gain any access to the water. Rivers support fish and if that water's in a barrel, there's not gonna be that many fish who start to live. Our rivers essentially give you recreation. You can swim in a river. You can't swim in a barrel. All of the common uses that one would like to have with respect to all water when you talk about nutrition, fishing, recreation, navigation. Occupadio is forbidden and now we're effect all of these particular rights are going to be preserved one way or another.