“It is not easy to see why any deep human instinct should need reinforcement through law. There is no law commanding men to eat and drink, or forbidding them to put their hands in the fire. Men eat and drink and keep their hands out of the fire instinctively, for fear of natural, not legal penalties, which would be entailed by violence done to these instincts. The law only forbids men to do what their instincts incline them to do; what nature itself prohibits and punishes it would be superfluous for the law to prohibit and punish. Accordingly we may always safely assume that crimes forbidden by law are crimes which many men have a natural propensity to commit. If there were no such propensity there would be no such crimes, and if no such crimes were committed, what need to forbid them? Instead of assuming therefore, from the legal prohibition of incest, that there is a natural aversion to incest we ought rather to assume that there is a natural instinct in favour of it, and that if the law represses it, it does so because civilized men have come to the conclusion that the satisfaction of these natural instincts is detrimental to the general interests of society”[182]. To this valuable argument of Frazer’s I can add that the experiences of psychoanalysis make the assumption of such an innate aversion to incestuous relations altogether impossible. They have taught, on the contrary, that the first sexual impulses of the young are regularly of an incestuous nature and that such repressed impulses play a rôle which can hardly be overestimated as the motive power of later neuroses. The interpretation of incest dread as an innate instinct must therefore be abandoned. The same holds true of another derivation of the incest prohibition which counts many supporters, namely the assumption that primitive races very soon observed the dangers with which inbreeding threatened their race and that they therefore had decreed the incest prohibition with a conscious purpose. The objections to this attempted explanation crowd upon each other[183]. Not only must the prohibition of incest be older than all breeding of domestic animals from which men could derive experience of the effect of inbreeding upon the characteristics of the breed, but the harmful consequences of inbreeding are not established beyond all doubt even to-day and in man they can be shown only with difficulty. Besides, everything that we know about contemporaneous savages makes it very improbable that the thoughts of their far-removed ancestors should already have been occupied with preventing injury to their later descendants. It sounds almost ridiculous to attribute hygienic and eugenic motives such as have hardly yet found consideration in our culture, to these children of the race who lived without thought of the morrow[184].