But a consistent theory of liberty could not rest wholly satisfied with the actual system under which property is held. The first point of attack, already pressed by the disciples of Cobden, was the barrier to free exchange in the matter of land. It was not and still is not easy for the landless to acquire land, and in the name of free contract Cobden and his disciples pressed for cheap and unimpeded transfer. But a more searching criticism was possible. Land is limited in amount, certain kinds of land very narrowly limited. Where there is limitation of supply monopoly is always possible, and against monopoly the principles of free competition declared war. To Cobden himself, free trade in land was the pendant to free trade in goods. But the attack on the land monopoly could be carried much further, and might lead the individualist who was in earnest about his principles to march a certain distance on parallel lines with the Socialist enemy. This has, in fact, occurred in the school of Henry George. This school holds by competition, but by competition only on the basis of a genuine freedom and equality for all individuals. To secure this basis, it would purge the social system of all elements of monopoly, of which the private ownership of land is in its view the most important. This object, it maintains, can be secured only through the absorption by the State of all elements of monopoly value. Now, monopoly value accrues whenever anything of worth to men of which the supply is limited falls into private hands. In this case competition fails. There is no check upon the owner except the limitations of demand. He can exact a price which bears no necessary relation to the cost of any effort of his own. In addition to normal wages and profits, he can extract from the necessities of others a surplus, to which the name of economic rent is given. He can also hold up his property and refuse to allow others to make use of it until the time when its full value has accrued, thereby increasing the rent which he will ultimately receive at the cost of much loss in the interim to society.