 What we might call equal share left-libertarianism—advocated by Henry George (1879) and Hillel Steiner (1994), for example—interprets the Lockean proviso as requiring equally valuable shares of natural resources for everyone. Thus, while individuals are morally free to use or appropriate natural resources, those who thereby acquire more than their share (understood in terms of per capita value) owe compensation to others. This constraint is enduring significance. It applies at the moment of appropriation, and encumbers subsequent through time. Others claim that the equality requirement is supposed to also compensate for disadvantages that result from different natural abilities (such as the effects of genetic differences). Thus, Otsuka (2003) claims that the Lockean proviso prohibits appropriations that diminish the opportunities of others for well-being beyond the opportunity obtained by appropriating or using a natural resource.