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.  But when, owing to political causes, the Jesuits were driven from the country, the natives sank back into their previous industrial helplessness.  The temporary efficiency of their labour had been due to the ability that directed it; and as soon as that ability was withdrawn, the labour, left to itself, shrank again to its old relative inefficiency.  Now, here we have a case precisely analogous to that which we have to deal with when considering at the present day how much of the products of any civilised nation is produced by the labour of the average units of the population, and how much by the ability of the exceptional men directing them.  It is not a question of how much this or that group of labourers, which is directed by a man of the highest grade of ability, produces in excess of the products of some similar group which is directed by another man whose ability is somewhat inferior; it is a question of how much the same nation would produce, if every director of other men’s labour were withdrawn, and the present labouring units left to their own devices.

These two questions, though not mutually exclusive, differ as much as the question of why one of two balloons rises above the earth to a height of three miles and a furlong, while a second balloon reaches the height of three miles only, differs from the question of why either of them rises in the air at all.  Mr. Webb and his friends, with their theory of the rent of ability, confine themselves to the first of these—­namely, the question of why one balloon rises a furlong higher than the other.  The real question which we have to deal with here is why both balloons lift their aeronauts at least three miles into the clouds, while other men who have no balloon to lift them can get no higher than the top of the church steeple.  Or to come back to literal fact, our problem must be expressed thus:  Let us take the present population of Great Britain or America, and, having noted the