According to Starcke, "we are in some respects disposed to underestimate the great influence which sexual matters exert on all the concerns of social life, and the attempt is sometimes made to sever it from moral life, as a matter of which we are constrained to admit the practical existence, although, from the ideal point of view, it ought not to be. On the other hand, its influence on primitive communities has been greatly overrated." The sexual instinct, however powerful, is "devoid of the conditions which form the basis of the leading tendencies in which man's struggle for existence must be fought out." Hence primitive marriage does not rest upon the tender sentiment which we call love,[296] but "as hard and dry as private life itself," it has its "origin in the most concrete and prosaic requirements." The "common household," he continues, "in which each had a given work to do, and the common interest of obtaining and rearing children were the foundations upon which marriage was originally built."[297] Therefore, according to this view, marriage appears to be a kind of contractual relation from the beginning.[298] The conclusions of Westermarck on this point are in substantial harmony with those of Starcke: "The prolonged union of the sexes is, in some way or other, connected with parental duties.... The tie which joins male and female is an instinct developed through the powerful influence of natural selection." This instinct as well as parental affection are "thus useful mental dispositions which, in all probability, have been acquired through the survival of the fittest." So he concludes that "it is for the benefit of the young that male and female continue to live together. Marriage is therefore rooted in family, rather than family in marriage."[299] Hence it is that among many peoples "true conjugal life does not begin before a child is born;" and there are other races who "consider that the birth of a child out of wedlock makes it obligatory for the parents to marry."[300] [296] Compare the interesting chapter of HELLWALD, "Kuss und Liebe," _op. cit._, 97-120. [297] _Primitive Family_, 241, 242, 268, and the whole of chap. vii, of the second division of the work, in which he gives the results of the researches comprised in the preceding chapters. _Cf._ DARGUN, _Mutterrecht und Vaterrecht_, 17, 18, who favors Starcke's view as against HELLWALD, _op. cit._, 457; also LIPPERT, _Geschichte der Familie_, 118, who takes a similar position.