As it is easy to see, looking at our own ideas on parental kinship, all the normative ideas, whether religious, moral or legal, are in close connection with the central, basic idea, _i. e._ in the case of our society, the idea of consanguinity. And these normative ideas are brought by the collective mind into causal connection with the central idea of community of blood.[537] It would be the ideal of sociological research as regards our present subject if we could bring in any given society all the normative ideas into such a causal dependence upon the central idea, and explain how they are conceived by the collective mind as the outgrowth of this root idea; thus showing how all the legal, moral and customary aspects converge on the fundamental concept of kinship. Unhappily, in low societies the imperfection of ethnographic material would frustrate any attempt at such an enterprise. In Australia our knowledge of these aspects--moral, legal and customary--is very scanty. Although they are all undoubtedly in quite a rudimentary state, careful investigation would possibly disclose many points of extreme interest. [537] It is impossible to develop here this thought, which would require a volume if regard be had to the complexity of the fact. The references to higher societies are given by way of illustration only. One other problem must be discussed here more in detail, owing to its great theoretical importance, viz. the legal aspect of parental kinship. We have defined above the meaning of the word _legal_.[538] In connection with what has been said, we may affirm that the _legal_ is only one of the many aspects of kinship; that legal ideas, as far as known for any given society, must be taken into account when defining kinship, but that the latter cannot possibly be reduced to its legal aspect only. And it is still more incorrect[539] to represent physiological consanguinity and legal power over the child as two mutually exclusive sets of facts beyond which there can be no determination of parental kinship. We find the opinion expressed by many authors, especially with regard to Australia, that where-ever the tie binding parent and child was not constituted by the acknowledgment of consanguinity, that there always it was based on legal principles such as potestas, authority, _Machtstellung_, or other similar ones. [538] See above, p. 11. [539] Comparing what we have said above on consanguinity.