The diminution of numbers, in all likelihood, will rectify itself in time through the elimination of those characteristics which at present lead to a small birth-rate. Men and women who can still believe the Catholic faith will have a biological advantage; gradually a race will grow up which will be impervious to all the assaults of reason, and will believe imperturbably that limitation of families leads to hell-fire. Women who have mental interests, who care about art or literature or politics, who desire a career or who value their liberty, will gradually grow rarer, and be more and more replaced by a placid maternal type which has no interests outside the home and no dislike of the burden of motherhood. This result, which ages of masculine domination have vainly striven to achieve, is likely to be the final outcome of women’s emancipation and of their attempt to enter upon a wider sphere than that to which the jealousy of men confined them in the past. Perhaps, if the facts could be ascertained, it would be found that something of the same kind occurred in the Roman Empire. The decay of energy and intelligence during the second, third, and fourth centuries of our era has always remained more or less mysterious. But there is reason to think that then, as now, the best elements of the population in each generation failed to reproduce themselves, and that the least vigorous were, as a rule, those to whom the continuance of the race was due. One might be tempted to suppose that civilization, when it has reached a certain height, becomes unstable, and tends to decay through some inherent weakness, some failure to adapt the life of instinct to the intense mental life of a period of high culture. But such vague theories have always something glib and superstitious which makes them worthless as scientific explanations or as guides to action. It is not by a literary formula, but by detailed and complex thought, that a true solution is to be found. Let us first be clear as to what we desire. There is no importance in an increasing population; on the contrary, if the population of Europe were stationary, it would be much easier to promote economic reform and to avoid war. What is regrettable _at present_ is not the decline of the birth-rate in itself, but the fact that the decline is greatest in the best elements of the population. There is reason, however, to fear in the future three bad results: first, an absolute decline in the numbers of English, French, and Germans; secondly, as a consequence of this decline, their subjugation by less civilized races and the extinction of their tradition; thirdly, a revival of their numbers on a much lower plane of civilization, after generations of selection of those who have neither intelligence nor foresight. If this result is to be avoided, the present unfortunate selectiveness of the birth-rate must be somehow stopped.