Both Lubbock and Spencer, it will be observed, agree with McLennan in assigning the origin of exogamy to wife-capture. On the other hand, a group of writers, differing widely on ancillary questions, unite in identifying the causes which have produced exogamy with those which, in general, have led to the establishment of forbidden degrees of consanguinity in marriage. In other words, tribal or clan exogamy is but one of many rules for the prevention of close intermarriage between kindred. It must be admitted that a profound horror of incest is now "an almost universal characteristic of mankind, the cases which seem to indicate a perfect absence of this feeling being so exceedingly rare that they must be regarded merely as anomalous aberrations from a general rule."[366] But, from the beginning, has there been an innate aversion to the sexual union of persons closely related by blood? Is that aversion derived from experience of the injurious results of such unions? Did it originally extend only to marriage and not to irregular sexual connections? Or, finally, is it the indirect result of a custom, such as wife-capture, hardening into a rule of forbidden degrees? These are questions to which very different answers have been given. [366] WESTERMARCK, _op. cit._, 290. Adherents of the horde theory, of course, deny that horror of incest is a primitive instinct. Such is the view also of Spencer, who thinks that "regular relations of the sexes are results of evolution, and that the sentiments upholding them have been gradually established,"[367] though--somewhat inconsistently, as we have seen--he agrees with McLennan in regarding exogamy as the result of custom growing into law. Lubbock takes a similar position, denying that we can "attribute to savages any such farsighted ideas" as the recognition of the injurious effects of close intermarriage.[368] On the other hand, Morgan, whose consanguine family implies the absence of any primitive abhorrence of incest, considers exogamy "explainable, and only explainable as a reformatory movement to break up the intermarriage of blood relations," thus implying that the aversion to such a union is derived from experience.[369] But knowledge which "can only be gained by lengthened observation," Dr. Peschel believes, "is 'unattainable by unsettled and childishly heedless races,' among whom, nevertheless, a horror of incest is developed most strongly."[370] Sir Henry Maine, on the contrary, "cannot see why the men who discovered the use of fire and selected the wild forms of certain animals for domestication and of vegetables for cultivation should not find out that children of unsound constitution were born of nearly related parents."[371] The researches of Starcke, and still more those of Westermarck, render it almost certain, however, that Morgan and Maine are mistaken in their view, though it may point the way to the truth.[372] [367] SPENCER, _op. cit._, I, 636 ff. [368] LUBBOCK, _op. cit._, 133.