of Darwin’s selective theory), ’the saying that beauty is but skin-deep is itself but a skin-deep saying.’  In reality, beauty is one of the very best guides we can possibly have to the desirability, so far as race-preservation is concerned, of any man or any woman as a partner in marriage.  A fine form, a good figure, a beautiful bust, a round arm and neck, a fresh complexion, a lovely face, are all outward and visible signs of the physical qualities that on the whole conspire to make up a healthy and vigorous wife and mother; they imply soundness, fertility, a good circulation, a good digestion.  Conversely, sallowness and paleness are roughly indicative of dyspepsia and anaemia; a flat chest is a symptom of deficient maternity; and what we call a bad figure is really, in one way or another, an unhealthy departure from the central norma and standard of the race.  Good teeth mean good deglutition; a clear eye means an active liver; scrubbiness and undersizedness mean feeble virility.  Nor are indications of mental and moral efficiency by any means wanting as recognised elements in personal beauty.  A good-humoured face is in itself almost pretty.  A pleasant smile half redeems unattractive features.  Low, receding foreheads strike us unfavourably.  Heavy, stolid, half-idiotic countenances can never be beautiful, however regular their lines and contours.  Intelligence and goodness are almost as necessary as health and vigour in order to make up our perfect ideal of a beautiful human face and figure.  The Apollo Belvedere is no fool; the murderers in the Chamber of Horrors at Madame Tussaud’s are for the most part no beauties.

What we all fall in love with, then, as a race, is in most cases efficiency and ability.  What we each fall in love with individually is, I believe, our moral, mental, and physical complement.  Not our like, not our counterpart; quite the contrary; within healthy limits, our unlike and our opposite.  That this is so has long been more or less a commonplace of ordinary conversation; that it is scientifically true, one time with another, when we take an extended range of cases, may, I think, be almost demonstrated by sure and certain warranty of human nature.

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