idea of
what the individual really is, by examining sisters and brothers; and in
the second place, there will be less danger of a childless marriage,
since it is already proved that the individual comes of a fertile stock.
Francis Galton showed clearly the havoc wrought in the English peerage,
by marriages with heiresses (an heiress there being nearly always an
only child). Such women were childless in a much larger proportion than
ordinary women.

"Marrying a man to reform him" is a speculation in which many women have
indulged and usually--it may be said without fear of contradiction--with
unfortunate results. It is always likely that she will fail to reform
him; it is certain that she can not reform his germ-plasm. Psychologists
agree that the character of a man or woman undergoes little radical
change after the age of 25; and the eugenist knows that it is largely
determined, _potentially_, when the individual is born. It is,
therefore, in most cases the height of folly to select a partner with
any marked undesirable trait, with the idea that it will change after a
few years.

All these suggestions have in general been directed at the young man or
woman, but it is admitted that if they reach their target at all, it is
likely to be by an indirect route. No rules or devices can take the
place, in influencing sexual selection, of that lofty and rational ideal
of marriage which must be brought about by the uplifting of public
opinion. It is difficult to bring under the control of reason a subject
that has so long been left to caprice and impulse; yet much can
unquestionably be done, in an age of growing social responsibility, to
put marriage in a truer perspective. Much is already being done, but not
in every case of change is the future biological welfare of the race
sufficiently borne in mind. The interests of the individual are too
often regarded to the exclusion of posterity. The eugenist would not
sacrifice the individual, but he would add the welfare of posterity to
that of the individual, when the standards of sexual selection are being
fixed. It is only necessary to make the young person remember that he
will marry, not merely an individual, but a family; and that not only
his own happiness but to some extent the quality of future generations
is being determined by his choice.

We must have (1) the proper ideals of mating but (2) these ideals must
be realized. It is known that many young people have the highe