han to be quite sure of good stocks. Both on
the scientific side and on the social side, however, we are beginning to
attain a clearer realization of the end to be attained and a more precise
knowledge of the methods of attaining it.[461]

Even when we have gained a fairly clear conception of the stocks and the
individuals which we are justified in encouraging to undertake the task of
producing fit citizens for the State, the problems of procreation are by
no means at an end. Before we can so much as inquire what are the
conditions under which selected individuals may best procreate, there is
still the initial question to be decided whether those individuals are
both fertile and potent, for this is not guaranteed by the fact that they
belong to good stocks, nor is even the fact that a man and a woman are
fertile with other persons any positive proof that they will be fertile
with each other. Among the large masses of the population who do not seek
to make their unions legal until those unions have proved fertile, this
difficulty is settled in a simple and practical manner. The question is,
however, a serious and hazardous one, in the present state of the marriage
law in most countries, for those classes which are accustomed to bind
themselves in legal marriage without any knowledge of their potency and
fertility with each other. The matter is mostly left to chance, and as
legal marriage cannot usually be dissolved on the ground that there are no
offspring, even although procreation is commonly declared to be the chief
end of marriage, the question assumes much gravity. The ordinary range of
sterility is from seven to fifteen per cent. of all marriages, and in a
very large proportion of these it is a source of great concern. This could
be avoided, in some measure, by examination before marriage, and almost
altogether by ordaining that, as it is only through offspring that a
marriage has any concern for the State, a legal marriage could be
dissolved, after a certain period, at the will of either of the parties,
in the absence of such offspring.

It was formerly supposed that when a union proved infertile, it
was the wife who was at fault. That belief is long since
exploded, but, even yet, a man is generally far more concerned
about his potency, that is, his ability to perform the mechanical
act of coitus, than about his fertility, that is, his ability to
produce living spermatozoa, though the latte