Brothers and sisters have more in common, mentally and physically, than any other members of the same race can possibly have with one another. But nobody falls in love with his sister. A profound instinct has taught even the lower races of men (for the most part) to avoid such union of the all-but-identical. In the higher races the idea never so much as occurs to us. Even cousins seldom fall in love—seldom, that is to say, in comparison with the frequent opportunities of intercourse they enjoy, relatively to the remainder of general society. When they do, and when they carry out their perilous choice effectively by marriage, natural selection soon avenges Nature upon the offspring by cutting off the idiots, the consumptives, the weaklings, and the cripples, who often result from such consanguineous marriages. In narrow communities, where breeding in-and-in becomes almost inevitable, natural selection has similarly to exert itself upon a crowd of crétins and other hapless incapables. But in wide and open champaign countries, where individual choice has free room for exercise, men and women as a rule (if not constrained by parents and moralists) marry for love, and marry on the whole their natural complements. They prefer outsiders, fresh blood, somebody who comes from beyond the community, to the people of their own immediate surroundings. In many men the dislike to marrying among the folk with whom they have been brought up amounts almost to a positive instinct; they feel it as impossible to fall in love with a fellow-townswoman as to fall in love with their own first cousins. Among exogamous tribes such an instinct (aided, of course, by other extraneous causes) has hardened into custom; and there is reason to believe (from the universal traces among the higher civilisations of marriage by capture) that all the leading races of the world are ultimately derived from exogamous ancestors, possessing this healthy and excellent sentiment.
In minor matters, it is of course universally admitted that short men, as a rule, prefer tall women, while tall men admire little women. Dark pairs by preference with fair; the commonplace often runs after the original. People have long noticed that this attraction towards one's opposite tends to keep true the standard of the race; they have not, perhaps, so generally observed that it also indicates roughly the existence in either individual of a desire for its own natural complement. It is difficult here to give definite examples, but everybody knows how, in the subtle psychology of Falling in Love, there are involved innumerable minor elements, physical and mental, which strike us exactly because of their absolute adaptation to form with ourselves an adequate union. Of course we do not definitely seek out and discover such qualities; instinct works far more intuitively than that; but we find at last, by subsequent observation, how true and how trustworthy were its immediate indications. That is to say, those men do so who were wise enough or fortunate enough to follow the earliest promptings of their own hearts, and not to be ashamed of that divinest and deepest of human intuitions, love at first sight.
How very subtle this intuition is, we can only guess in part by the apparent capriciousness and incomprehensibility of its occasional action. We know that some men and women fall in love easily, while others are only moved to love by some very special and singular combination of peculiarities. We know that one man is readily stirred by every pretty face he sees, while another man can only be roused by intellectual qualities or by moral beauty. We know that sometimes we meet people possessing every virtue and grace under heaven, and yet for some unknown and incomprehensible reason we could no more fall in love with them than we could fall in love with the Ten Commandments. I don't, of course, for a moment accept the silly romantic notion that men and women fall in love only once in their lives, or that each one of us has somewhere on earth his or her exact affinity, whom we must sooner or later meet or else die unsatisfied. Almost every healthy normal man or woman has probably fallen in love over and over again in the course of a lifetime (except in case of very early marriage), and could easily find dozens of persons with whom they would be capable of falling in love again if due occasion offered. We are not all created in pairs, like the Exchequer tallies, exactly intended to fit into one another's minor idiosyncrasies. Men and women as a rule very sensibly fall in love with one another in the particular places and the particular societies they happen to be cast among. A man at Ashby-de-la-Zouch does not hunt the world over to find his pre-established harmony at Paray-le-Monial or at Denver, Colorado. But among the women he actually meets, a vast number are purely indifferent to him; only one or two, here and there, strike him in the light of possible wives, and only one in the last resort (outside Salt Lake City) approves herself to his inmost nature as the actual wife of his final selection.
Now this very indifference to the vast mass of our fellow-countrymen or fellow-countrywomen, this extreme pitch of selective preference in the human species, is just one mark of our extraordinary specialisation, one stamp and token of our high supremacy. The brutes do not so pick and choose, though even there, as Darwin has shown, selection plays a large part (for the very butterflies are coy, and must be wooed and won). It is only in the human race itself that selection descends into such minute, such subtle, such indefinable discriminations. Why should a universal and common impulse have in our case these special limits? Why should we be by nature so fastidious and so diversely affected? Surely for some good and sufficient purpose. No deep-seated want of our complex life would be so narrowly restricted without a law and a meaning. Sometimes we can in part explain its conditions. Here, we see that beauty plays a great rôle; there, we recognise the importance of strength, of manner, of grace, of moral qualities. Vivacity, as Mr. Galton justly remarks, is one of the most powerful among human attractions, and often accounts for what might otherwise seem unaccountable preferences. But after all is said and done, there remains a vast mass of instinctive and inexplicable elements: a power deeper and more marvellous in its inscrutable ramifications than human consciousness. 'What on earth,' we say, 'could So-and-so see in So-and-so to fall in love with?' This very inexplicability I take to be the sign and seal of a profound importance. An instinct so conditioned, so curious, so vague, so unfathomable, as we may guess by analogy with all other instincts, must be Nature's guiding voice within us, speaking for the good of the human race in all future generations.
On the other hand, let us suppose for a moment (impossible supposition!) that mankind could conceivably divest itself of 'these foolish ideas about love and the tastes of young people,' and could hand over the choice of partners for life to a committee of anthropologists, presided over by Sir George Campbell. Would the committee manage things, I wonder, very much better than the Creator has managed them? Where would they obtain that intimate knowledge of individual structures and functions and differences which would enable them to join together in holy matrimony fitting and complementary idiosyncrasies? Is a living man, with all his organs, and powers, and faculties, and dispositions, so simple and easy a problem to read that anybody else can readily undertake to pick out off-hand a help meet for him? I trow not! A man is not a horse or a terrier. You cannot discern his 'points' by simple inspection. You cannot see à priori why a Hanoverian bandsman and his heavy, ignorant, uncultured wife, should conspire to produce a Sir William Herschel. If you tried to improve the breed artificially, either by choice from outside, or by the creation of an independent moral sentiment, irrespective of that instinctive preference which we call Falling in Love, I believe that so far from improving man, you would only do one of two things—either spoil his constitution, or produce a tame stereotyped pattern of amiable imbecility. You would crush out all initiative, all spontaneity, all diversity, all originality; you would get an animated moral code instead of living men and women.
Look at the analogy of domestic animals. That is the analogy to which breeding reformers always point with special pride: but what does it really teach us? That you can't improve the efficiency of animals in any one point to any high degree, without upsetting the general balance of their constitution. The race-horse can run a mile on a particular day at a particular place, bar accidents, with wonderful speed: but that is about all he is good for. His health as a whole is so surprisingly feeble that he has to be treated with as much care as a delicate exotic. 'In regard to animals and plants,' says Sir George Campbell, 'we have very largely mastered the principles of heredity and culture, and the modes by which good qualities may be maximised, bad qualities minimised.' True, so far as concerns a few points prized by ourselves for our own purposes. But in doing this, we have so lowered the general constitutional vigour of the plants or animals that our vines fall an easy prey to oidium and phylloxera, our potatoes to the potato disease and the Colorado beetle; our sheep are stupid, our rabbits idiotic, our domestic breeds generally threatened with dangers to life and limb unknown to their wiry ancestors in the wild state. And when one comes to deal with the infinitely more complex individuality of man, what hope would there be of our improving the breed by deliberate selection? If we developed the intellect, we would probably stunt the physique or the moral nature; if we aimed at a general culture of all faculties alike, we would probably end by a Chinese uniformity of mediocre dead level.
The balance of organs and faculties in a race is a very delicate organic equilibrium. How delicate we now know from thousands of examples, from the correlations of seemingly unlike parts, from the wide-spread effects of small conditions, from the utter dying out of races like the Tasmanians or the Paraguay Indians under circumstances different from those with which their ancestors were familiar. What folly to interfere with a marvellous instinct which now preserves this balance intact, in favour of an untried artificial system which would probably wreck it as helplessly as the modern system of higher education for women is wrecking the maternal powers of the best class in our English community!
Indeed, within the race itself, as it now exists, free choice, aided by natural selection, is actually improving every good point, and is for ever weeding out all the occasional failures and shortcomings of nature. For weakly children, feeble children, stupid children, heavy children, are undoubtedly born under this very régime of falling in love, whose average results I believe to be so highly beneficial. How is this? Well, one has to take into consideration two points in seeking for the solution of that obvious problem.
In the first place, no instinct is absolutely perfect. All of them necessarily fail at some points. If on the average they do good, they are sufficiently justified. Now the material with which you have to start in this case is not perfect. Each man marries, even in favourable circumstances, not the abstractly best adapted woman in the world to supplement or counteract his individual peculiarities, but the best woman then and there obtainable for him. The result is frequently far from perfect; all I claim is that it would be as bad or a good deal worse if somebody else made the choice for him, or if he made the choice himself on abstract biological and 'eugenic' principles. And, indeed, the very existence of better and worse in the world is a condition precedent of all upward evolution. Without an overstocked world, with individual variations, some progressive, some retrograde, there could be no natural selection, no survival of the fittest. That is the chief besetting danger of cut-and-dried doctrinaire views. Malthus was a very great man; but if his principle of prudential restraint were fully carried out, the prudent would cease to reproduce their like, and the world would be peopled in a few generations by the hereditarily reckless and dissolute and imprudent. Even so, if eugenic principles were universally adopted, the chance of exceptional and elevated natures would be largely reduced, and natural selection would be in so much interfered with or sensibly retarded.
In the second place, again, it must not be forgotten that falling in love has never yet, among civilised men at least, had a fair field and no favour. Many marriages are arranged on very different grounds—grounds of convenience, grounds of cupidity, grounds of religion, grounds of snobbishness. In many cases it is clearly demonstrable that such marriages are productive in the highest degree of evil consequences. Take the case of heiresses. An heiress is almost by necessity the one last feeble and flickering relic of a moribund stock—often of a stock reduced by the sordid pursuit of ill-gotten wealth almost to the very verge of actual insanity. But let her be ever so ugly, ever so unhealthy, ever so hysterical, ever so mad, somebody or other will be ready and eager to marry her on any terms. Considerations of this sort have helped to stock the world with many feeble and unhealthy persons. Among the middle and upper classes it may be safely said only a very small percentage of marriages is ever due to love alone; in other words, to instinctive feeling. The remainder have been influenced by various side advantages, and nature has taken her vengeance accordingly on the unhappy offspring. Parents and moralists are ever ready to drown her voice, and to counsel marriage within one's own class, among nice people, with a really religious girl, and so forth ad infinitum. By many well-meaning young people these deadly interferences with natural impulse are accepted as part of a higher and nobler law of conduct. The wretched belief that one should subordinate the promptings of one's own soul to the dictates of a miscalculating and misdirecting prudence has been instilled into the minds of girls especially, until at last many of them have almost come to look upon their natural instincts as wrong, and the immoral, race-destructive counsels of their seniors or advisers as the truest and purest earthly wisdom. Among certain small religious sects, again, such as the Quakers, the duty of 'marrying in' has been strenuously inculcated, and only the stronger-minded and more individualistic members have had courage and initiative enough to disregard precedent, and to follow the internal divine monitor, as against the externally-imposed law of their particular community. Even among wider bodies it is commonly held that Catholics must not marry Protestants; and the admirable results obtained by the mixture of Jewish with European blood have almost all been reached by male Jews having the temerity to marry 'Christian' women in the face of opposition and persecution from their co-nationalists. It is very rarely indeed that a Jewess will accept a European for a husband. In so many ways, and on so many grounds, does convention interfere with the plain and evident dictates of nature.