"The theory which bases the right of property on labour really depends in the ultimate resort on the right of possession and the fact that it is socially expedient, and is therefore upheld by the laws of society. Grotius, discussing this in the old Roman days, pointed out that since nothing can be made except out of pre-existing matter, acquisition by means of labour depends, ultimately, on possession by means of occupation."[20] Since man's right to his faculties does not of itself give him a right to exercise them upon material objects, productive labour cannot of itself give him a right to the product therefrom created, nor constitute the original title of ownership. Since labour is not the original title to property, it is not the only possible title to property in land. Hence the fact that labour does not produce land, has no bearing on the question of private landownership. In passing it may be observed that Henry George implicitly admitted that the argument from the labour title was not of itself sufficient to disprove the right of private property in land. Considering the objection, "if private property in land be not just, then private property in the products of land is not just, as the material of these products is taken from the land," he replied that the latter form of ownership "is in reality a mere right of temporary possession," since the raw material in the products sooner or later returns to the "reservoirs provided for all ... and thus the ownership of them by one works no injury to others."[21] But private ownership of land, he continued, shuts out others from the very reservoirs. Here we have a complete abandonment of the principle which underlies the labour argument. Instead of trying to show from the nature of the situation that there is a logical difference between the two kinds of ownership, he shifts his ground to a consideration of consequences. He makes the title of social utility instead of the title of labour the distinguishing and decisive consideration. As we shall see later, he is wrong even on this ground; for the fundamental justification of private landownership is precisely the fact that it is the system of land tenure most conducive to human welfare. At present we merely call attention to the breakdown in his own hands of the labour argument.