A lot has been written about the theory of property. Property has been and remains one of the bedrock subjects of social science theorizing. In its rights form (the idea that property is a bundle of rights!) property continues to be a key target for philosophical analysis. While the literature on property is vast, relatively little of it has explicitly dealt with intellectual property. It may be that the assumption has been that any general theory of property illuminates all property forms, including intellectual property. Perhaps this assumption is correct and perhaps not. Like other property rights, intellectual property rights are relations between individuals. Unlike real property law, intellectual property law posits rights in abstract objects. An algorithm and the formulae for penicillin and its derivatives are examples of abstract objects. Many people need, use and depend on such objects. Many of the relationships of interdependence that characterize social life and work in modern 'on-line' societies are linked to such objects. A property form that allows private hands to capture important abstract objects creates, amongst other things, many person-dependent relationships in a society. It swells the growth of private power. The negative liberty of individuals, the right not to be interfered with, faces greater dangers. There is a lot at stake when property extends its reach to abstract objects. For these reasons at least it seems worth asking whether we can accommodate intellectual property within one or more of the existing general accounts of property or whether we should develop a distinctive theory of intellectual property.