They assume as their starting-point, in every case, the presence of directive ability sufficient to organise the labourers in such a way that the products of the entire group shall provide the labourers with wages which are up to a certain standard, and a minimum of profit or of surplus values besides.

This lowest grade of ability is one of the postulates of their argument, just as in calculating agricultural rent the first postulate of our argument is a lowest grade of land.
Now, in connection with many questions of a more or less limited kind, this assimilation of the products of superior ability to rent, and of ability of a lower grade to land which is practically rentless, will serve our purpose well enough.

Between the two cases, however, there is a vast and underlying difference; and when we consider our present problem under its widest and most vital aspect, it is the difference, not the likeness, between them, which constitutes our main concern.

The nature of this difference has been pointed out already.

When we are discussing rent and agriculture, land is a necessary assumption, for unless there were land, there could be no agriculture at all; but there can be, has been, and still is in the world, abundance of labour without directive ability; and while it would be meaningless to ask what would happen to rent if all land disappeared, the question of what would happen to labour if all ability were in abeyance is precisely the question raised by all schemes of economic revolution, and one which has been constantly illustrated by the facts of economic history.
Of such facts we may take the following, picturesque example: In the eighteenth century the Jesuit Fathers in Uruguay succeeded in teaching the natives a variety of Western arts, among others that of watch-making, and so long as the Jesuits were on the spot to direct them the natives exhibited much manual skill.