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 role; 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.