Now to apply this principle to the adjustment of the claims of the community on the one hand and the producers or inheritors of wealth on the other would involve a discrimination of the factors of production which is not easy to make in all instances. If we take the case of urban land, referred to above, the distinction is tolerably clear. The value of a site in London is something due essentially to London, not to the landlord. More accurately a part of it is due to London, a part to the British empire, a part, perhaps we should say, to Western civilization. But while it would be impossible to disentangle these subsidiary factors, the main point that the entire increment of value is due to one social factor or another is sufficiently clear, and this explains why Liberal opinion has fastened on the conception of site value as being by right communal and not personal property. The monopoly value of licensed premises, which is the direct creation of laws passed for the control of the liquor traffic, is another case in point. The difficulty which society finds in dealing with these cases is that it has allowed these sources of wealth to pass out of its hands, and that property of these kinds has freely passed from one man to another in the market, in the belief that it stood and would stand on the same basis in law as any other. Hence, it is not possible for society to insist on the whole of its claim. It could only resume its full rights at the cost of great hardship to individuals and a shock to the industrial system. What it can do is to shift taxation step by step from the wealth due to individual enterprise to the wealth that depends on its own collective progress, thus by degrees regaining the ownership of the fruits of its own collective work.