This problem will form the subject of the sixth volume of the present series. In the meantime it may be suggested that we are easily credulous if we suppose that the problem has been finally disposed of by the peculiar progress of an abnormal century. But that experience has at least destroyed the view that there _need be_, or even is in fact in Western countries, a relation between real wages and the numbers of the people so close and direct that an improved standard of living must be temporary only, doomed to destroy itself by the increased population it engenders. One may perhaps go further and say that it is doubtful even in what direction changes in remuneration will influence the aggregate supply of labor. When we pass to "what should be," it is plain that there is nothing whatever to be said for the sort of relation indicated above. The view once widely held that the principle of population must inevitably keep the mass of people close to the verge of the bare means of subsistence was no statement of a desirable ideal. It was a nightmare; a nightmare none the less though it may haunt us yet. It is far from fanciful to suggest that it is because this relation is so obviously _not_ "what should be" that it may be ceasing to hold true in fact. But it would be very fanciful indeed to maintain that as yet "what should be" is represented by the actual population. Thus, just as with capital, so with labor, there is no reason to suppose that the aggregate supply is determined by any fundamental economic law, or corresponds in practice to what is socially desirable.