It can hardly be an accident that in this war the nations with a high birth-rate broke up in the order of their fecundity, while France stood like a rock. The sacrifice of comfort to numbers, which we have seen to be possible by maintaining a low standard of living, not only diminishes the happiness of a nation, and keeps it low in the scale of civilisation; it may easily prove to be a source of weakness in war. The expedients often advocated to encourage denser population--which those who urge them thoughtlessly assume to be a good thing--such as endowment of parenthood, and better housing at the expense of the taxpayer--have no effect except to penalise and sterilise those who pay the doles, for the benefit of those who receive them. They are intensely dysgenic in their operation, for they cripple and at last eliminate just those stocks which have shown themselves to be above the average in ability. The process has already advanced a long way, even without the reckless legislation which is now advocated. The lowest birth-rates, less than half that of the unskilled labourers, are those of the doctors, the teaching profession, and ministers of religion. The position of this class, intellectually and often physically the finest in the kingdom, is rapidly becoming intolerable, and it is the wastrels who mainly benefit by their spoliation. The causes of shrinkage in population are the opposites of those which we have found to promote its increase. The production of food may be diminished by the exhaustion of the soil, or by the progressive aridity caused by cutting down woods. The manufacture of goods to be exchanged for food may fall off owing to foreign competition, a result which is likely to follow from a rise in the standard of living, for the labourer then demands higher wages, and consumes more food per head, which of itself must check fertility, since the same amount of food will now support a smaller number. The delusion shared by the whole working class that they can make work for each other, at wages fixed by themselves, is ludicrous; a community cannot subsist 'by taking in each other's washing.' Or the supply of importable food may fail by the peopling up of the countries which grow it. Any conditions which make it no longer worth while to invest capital in business, or which destroy credit, have the same effect. One of the causes of the decay of the Roman Empire was the drain of specie to the East in exchange for perishable commodities. When trade is declining a general listlessness comes over the industrial world, and the output falls still further. There have been alleged instances of peoples which have dwindled and even disappeared from _taedium vitae_. This is said to have been the cause of the extinction of the Guanches of the Canary Islands; but the symptoms described rather suggest an outbreak of sleeping-sickness.