 Writing in a period of initial imperial expansion and discovery, Grotius in Mare Liberum (1609) defended the idea of common ownership of resources. By the term ‘common ownership’, Grotius meant that God granted all humans a right (a liberty right) to use objects or resources in the world to satisfy basic needs. In relation to the ocean, Grotius argued that no state or common power could claim exclusive dominion over it because the sea is not confinable within fixed boundaries and also is not amenable to transformation through human labor and so not an appropriate object of property rights. For these reasons, it should remain a relatively undisturbed commons; human beings would be free to travel on it and engage in mutual exchange, and to fish (the resources of the sea being, in his view, almost limitless). Although this view was challenged in his own day by John Selden in Mare Clausum (1635), who pointed out that geographical coordinates could enclose the sea, and in our own day by the recognition that the resources of the ocean and the seabed are not limitless, the idea of international rights over a global commons was very influential in the creation of modern international law, and was also important to the development of sea empires shortly thereafter (see Armitage 2012: 54–56). This idea is applied to many areas today as part of the idea of ‘common heritage of mankind’.