Instead of being limited mechanically by
caste, we begin to see that the choice of sexual mates must be limited
intelligently by actual fitness. Promiscuous marriages have never been the
rule; the possibility of choice has always been narrow, and the most
primitive peoples have exerted the most marked self-restraint. It is not
so merely among remote races but among our own European ancestors.
Throughout the whole period of Catholic supremacy the Canon law
multiplied the impediments to matrimony, as by ordaining that
consanguinity to the fourth degree (third cousins), as well as spiritual
relationship, is an impediment, and by such arbitrary prohibitions limited
the range of possible mates at least as much as it would be limited by the
more reasonable dictates of eugenic considerations.

At the present day it may be said that the principle of the voluntary
control of procreation, not for the selfish ends of the individual, but in
order to extinguish disease, to limit human misery, and to raise the
general level of humanity by substituting the ideal of quality for the
vulgar ideal of mere quantity, is now generally accepted, alike by medical
pathologists, embryologists and neurologists, and by sociologists and
moralists.

It would be easy to multiply quotations from distinguished
authorities on this point. Thus, Metchnikoff points out (_Essais
Optimistes_, p. 419) that orthobiosis seems to involve the
limitation of offspring in the fight against disease. Ballantyne
concludes his great treatise on _Antenanal Pathology_ with the
statement that "Eugenics" or well-begetting, is one of the
world's most pressing problems. Dr. Louise Robinovitch, the
editor of the _Journal of Mental Pathology_, in a brilliant and
thoughtful paper, read before the Rome Congress of Psychology in
1905, well spoke in the same sense: "Nations have not yet
elevated the energy of genesic function to the dignity of an
energy. Other energies known to us, even of the meanest grade,
have long since been wisely utilized, and their activities based
on the principle of the strictest possible economy. This economic
utilization has been brought about, not through any enforcement
of legislative restrictions, but through steadily progressive
human intelligence. Economic handling of genesic function will,
like the economic function of other energies, come about through
a steady and progr