I have spoken throughout, for argument’s sake, as though the only interest to be considered in the married relation were the interests of the offspring, and so ultimately of the race at large, rather than of the persons themselves who enter into it. But I do not quite see why each generation should thus be sacrificed to the welfare of the generations that afterwards succeed it. Now it is one of the strongest points in favour of the system of falling in love that it does, by common experience in the vast majority of instances, assort together persons who subsequently prove themselves thoroughly congenial and helpful to one another. And this result I look upon as one great proof of the real value and importance of the instinct. Most men and women select for themselves partners for life at an age when they know but little of the world, when they judge but superficially of characters and motives, when they still make many mistakes in the conduct of life and in the estimation of chances. Yet most of them find in after days that they have really chosen out of all the world one of the persons best adapted by native idiosyncrasy to make their joint lives enjoyable and useful. I make every allowance for the effects of habit, for the growth of sentiment, for the gradual approximation of tastes and sympathies; but surely, even so, it is a common consciousness with every one of us who has been long married, that we could hardly conceivably have made ourselves happy with any of the partners whom others have chosen; and that we have actually made ourselves so with the partners we chose for ourselves under the guidance of an almost unerring native instinct. Yet adaptation between husband and wife, so far as their own happiness is concerned, can have had comparatively little to do with the evolution of the instinct, as compared with adaptation for the joint production of vigorous and successful offspring. Natural selection lays almost all the stress on the last point, and hardly any at all upon the first one. If, then, the instinct is found on the whole so trustworthy in the minor matter, for which it has not specially been fashioned, how far more trustworthy and valuable must it probably prove in the greater matter—greater, I mean, as regards the interests of the race—for which it has been mainly or almost solely developed!