In the same way, when population shall have reached the extreme limit that all the land in the world can maintain, a law which, by gentle and infallible means prevents the further multiplication of mankind, cannot be considered either harsh or unjust. Now, it is landed property still which affords us solution of the difficulty. The institution of property, by applying the stimulant of self-interest, causes the land to produce the greatest possible [p271] quantity of subsistence, and by the division of inheritances puts each family in a situation to estimate the danger to itself of an imprudent multiplication. It is very clear that any other régime—Communism, for example—would be at once a less effective spur to production, and a less powerful curb to population. After all, it appears to me that Political Economy has discharged her duty when she has proved that the great and just law of the ‹mutuality of services› operates harmoniously, so long as human progress is not conclusively arrested. Is it not consoling to think that up to that point, and under the empire of freedom, it is not in the power of one class to oppress another? Is economic Science bound to solve this further problem: Given the tendency of mankind to multiply, what will take place when there is no longer room in the world for new inhabitants? Does God hold in reserve for that epoch some creative cataclasm, some marvellous manifestation of His almighty power? Or, as Christians, do we believe in the doctrine of the world’s destruction? These evidently are not economical problems, and there is no science which does not encounter similar difficulties. Natural philosophers know well, that all bodies which move on the surface of the earth have a tendency to descend, not to ascend. After all, a day must come when the mountains shall have filled up the valleys, when the embouchure of our rivers will be on the same level as their source, when the waters can no longer flow, etc., etc. What will happen then? Is Natural Science to cease to observe and to admire the harmony of the actual world because she cannot divine by what other harmony God will provide for a state of things far distant, no doubt, but inevitable? It seems to me that at this point the Economist, like the natural philosopher, should substitute for an exercise of curiosity an exercise of faith. He who has so marvellously arranged the medium in which we now live, knows best how to prepare another medium suitable to other circumstances. We judge of the productiveness of the soil and of human skill by the facts of which we are witnesses. Is this a rational mode of proceeding? Then, adopting it, we may say, Since it has required six thousand years to bring a tenth part of the earth to the sorry state of cultivation in which we find it, how many hundreds of ages must elapse before its entire surface shall be converted into a garden?