Is it credible, indeed, that the original male members of a group who had solely accepted his entry as mate for those ineligible females, their sisters, would consent to his further participation in marital right with other female group members? Evidently not: for thus the sexual prerogatives of the strangers would be much greater than their own--for the resident males are barred by the primal law from the wives of the new comers, who yet, as resident females, form probably much the most numerous section of the feminine element in the horde. If the new comers further inherited the ordinary right of intercourse with their own daughters, who would be correspondingly numerous, then the extent of their rights would entirely outbalance that of their brothers-in-law. As original residents the latter would, however, be the law-makers, and we can have no doubt as to what form in such a case law would take.[3] Thus is struck a blow again, however indirect, to incest as a custom, a blow whose power would be the more effective, insomuch as here it is the living father himself, in the outside suitor, who would be in cause. But even admitting that it is possible to conceive a complacency in regard to such participation in sexual rights on the part of the brother, there would still be another much more formidable obstacle to incestuous license as regards his daughter confronting the male intruder in the person of the precedent sister, now his wife. A psychological factor of enormous power was now for the first time in the history of the world to make itself felt. It would be the play of the natural feeling of sexual jealousy on the part of his resident female mate. The jealousy of a woman, in fact, is at length able to make its strength appear, to some purpose. As a wife who had not been captured, who, in fact, as an actual member of the group itself, was, so to speak, the capturer, her position in regard to her dependent husband would be profoundly modified in comparison with that of the ordinary captive female. Whereas such a captive, seized by the usual process of hostile capture, had been a mere chattel utterly without power; _she_, as a free agent in her own home, with her will backed by that of her brothers, could impose law on her subject spouse, and such law dictated by jealousy would undoubtedly ordain a bar to intercourse between him and her more youthful, and hence more attractive, daughter.