 However, things are not quite so clear-cut. Return to the question of exactly what rights individuals have on the libertarian view. The concept of self-ownership provides a large part of, but cannot provide the whole, answer to this question. For the world does not only contain people, but a wide variety of external resources, such as land. What kind of rights do we have in relation to these other resources? If we believe that individuals can come to have private property rights in these resources, no less inviolable than those they have in relation to their own bodies and abilities, we need to know how the individuals concerned acquire these property rights. Part of the answer the libertarian gives is that if we acquire a resource through voluntary exchange with someone who already owns it (legitimately), then we come to own the resource (an aspect of what Nozick calls “justice in transfer”; Nozick 1974: 150–153). But if we trace the history of such trades back there will be a point at which the resource in question did not have an owner; someone, somehow, made an unowned resource—a piece of land, say—their private property. But how can this happen? In Robert Nozick’s terms, the libertarian must given an account of “justice in acquisition” (Nozick 1974: 151, 174–182).