If you start looking at the Roman law in various kinds of areas, for example in its relationship to property, property held in common, property which was private, the Romans essentially had the right classification more or less for the right reason. They did not start from an abstract theory about what property rights were or how it is that they were supposed to be organized. What they did is they started with a fundamental distinction between common property and private property. Developed very briefly the attributes of common property, and then proceeded to talk about public property. And it's extremely important to understand this particular arrangement because what it does is it essentially gives a view of property rights which is wholly inconsistent with the modern views of property rights that developed through people like John Locke, James Madison, and so forth who overstate the importance of private property and systematically understate the importance of common property. So common property has the common feature. You're in a state of nature. So there's no state, and then there are certain forms of property to which everybody has access and from which nobody can be excluded. And that means in effect that if something is open to common access, then nobody by unilateral action can reduce it to his own private property. As for example by damming up a river, and claiming all the water that is poured into barrels as though it were his own. So that's the res commun. Now on the other side, you have something which is called res nullius, which literally means the things that are owned by nobody. And these things have exactly the opposite rules. If somebody engages in an act of occupation, taking possession in a way that indicates to the rest of the world that they're excluded from the thing in question, that thing becomes his or hers in perpetuity solely and exclusively and they're entitled to either develop it or to sell it in one form or another. if you go to Justinian ,what you're immediately told is that common property includes the water, the oceans, the rivers, the air, and consequently the seashore. These are things which are open to all that nobody can privatize. And then if you go a little bit further in Justinian and in Gaius, what they do is they announce that res nullius includes land, it includes wild animals, fish, birds, game. And it also includes sort of random things that you find on the seashore like a sea shell or something of that. And those are subject of the private regime.