Now, it is shown statistically that this falling off of fertility chiefly affects the classes above the average of ability, the upper and middle classes and also the superior part of the artisan classes[133]. These classes have been formed and are maintained by the operation of social and economic competition; they have long been, and are still, perpetually recruited in each generation from the lower strata, by the rise into them of the abler members of the lower strata. Hence, economic selection, under our present social system, seems to be working strongly for the mental deterioration of the most highly civilised peoples; the social ladder, becoming more nearly perfect, perpetually drains the mass of a people of its best members, enabling them to rise to the upper strata where they tend to become infertile[134]. Galton and Prof. Karl Pearson have insisted most strongly upon these tendencies. But they have not escaped the notice of continental authors. M. Jacobi[135] has written a large volume packed with historical illustrations to prove inductively the law that aristocracies always die out, or are only maintained by constant recruiting from below, or in other words that aristocracies tend to become infertile. And the modern tendency which we have just now considered under the head of economic selection may be regarded as falling under the head of this law, a case of the extension of the law to democratic communities and the natural aristocracies of ability which are generated in them. We may perhaps state the principal causes of this tendency in general terms as follows: the acquirement by any class of leisure, culture, and the habit of reflection (the malady of thought) partially emancipates that class from the empire of instinct, custom, and the religious sanctions of morality; and these are the great conservative agencies under the influence of which men not so emancipated continue to multiply according to the law of nature. These instincts, customs, and religious sanctions of morality, which lead men to multiply freely, have been acquired for the good of the race or of the society considered as an organism whose life is of indefinitely long duration; and in some respects they are opposed to the pleasure and welfare of the individual life. The habit of reason and reflection tends to lead men to act for their own immediate welfare, rather than for the future welfare of the race or of society, and to refuse to make those sacrifices of ease and to undertake those responsibilities and efforts which the care of a family imposes and which alone can secure the welfare of the future generations. It is in respect to these duties that the great antagonism between religion and reason appears in its most significant aspect.