grow up almost like brother and sister, and at the proper time fall violently in love with one another.  Who cannot recall in his own experience love marriages of schoolmates or of cousins living in intimate association from their childhood?  To say that such bringing up together creates “indifference” is obviously incorrect; to say that it leads to “aversion” is altogether unwarranted; and to trace to it such a feeling as our horror at the thought of marrying a sister, or mother, is simply preposterous.

The real source of the horror of incest in civilized communities was indicated more than two thousand years ago by Plato.  He believed that the reason why incestuous unions were avoided and abhorred, was to be found in the constant inculcation, at home and in literature, that

“They are unholy, hated of God, and most infamous....  Everyone from his earliest childhood has heard men speaking in the same manner about them always and everywhere, whether in comedy or in the graver language of tragedy.  When the poet introduces on the stage a Thyestes or an Oedipus, or a Macareus having secret intercourse with his sister, he represents him, when found out, ready to kill himself as the penalty of his sin.” (Laws, VIII., 838.)

Long before Plato another great “medicine man,” Moses, saw the necessity of enforcing a “taboo” against incest by the enactment of special severe laws relating to intercourse between relatives; and that there was no “instinct” against incest in his time is shown by the fact that he deemed it necessary to make such circumstantial laws for his own people, and by his specific testimony that “in all these things the nations are defiled which I cast out from before you, and the land is defiled.”  Regarding his motives in making such laws, Milman has justly remarked (H.J., I., 220),

“The leading principle of these enactments was to prohibit near marriage between those parties among whom, by the usage of their society, early and frequent intimacy was unavoidable and might lead to abuse.”

If Moses lived now, he would still be called upon to enact his laws; for to this day the horror of incest is a sentiment which it is necessary to keep up and enforce by education, moral precept, religion, and law.  It is no more innate or instinctive than the sentiment of modesty, the regard for chastity, or the disapproval of bigamy.  Children are not born with it any more than with the feeling that it is improper to be seen naked.  Medical writers bear witness to the wide prevalence of unnatural practices among children, even in good families, while in the slums of the large cities, where the families are herded like swine, there is a horrible indulgence in every kind of incest by adults as well as children.