Since marriage is restricted to particular classes, when there were but two gentes, one-half of all the females of one were, theoretically, the wives of one-half of all the males of the other. After their subdivision into six the benefit of marrying out of the gens, which was the chief advantage of the institution, was arrested, if not neutralized, by the presence of the classes together with the restrictions mentioned. It resulted in continuous in-and-in marriages beyond the immediate degree of brother and sister. If the gens could have eradicated the classes this evil would, in a great measure, have been removed.[48]
The organization into classes seems to have been directed to the single object of breaking up the intermarriage of brothers and sisters, which affords a probable explanation of the origin of the system. But since it did not look beyond this special abomination it retained a conjugal system nearly as objectionable, as well as cast it in a permanent form.
It remains to notice an innovation upon the original constitution of the classes, and in favor of the gens, which reveals a movement, still pending, in the direction of the true ideal of the gens. It is shown in two particulars: firstly, in allowing each triad of gentes to intermarry with each other, to a limited extent; and secondly, to marry into classes not before permitted. Thus, Iguana-Murri can now marry Mata in the Kangaroo gens, his collateral sister, whereas originally he was restricted to Buta in the opposite three. So Iguana-Kubbi can now marry Kapota, his collateral sister. Emu-Kumbo can now marry Buta, and Emu-Ippai can marry Ippata in the Blacksnake gens, contrary to original limitations. Each class of males in each triad of gentes seems now to be allowed one additional class of females in the two remaining gentes of the same triad, from which they were before excluded. The memoranda sent by Mr. Fison, however, do not show a change to the full extent here indicated.[49]
This innovation would plainly have been a retrograde movement but that it tended to break down the classes. The line of progress among the Kamilaroi, so far as any is observable, was from classes into gentes, followed by a tendency to make the gens instead of the class the unit of the social organism. In this movement the overshadowing system of cohabitation was the resisting element. Social advancement was impossible without diminishing its extent, which was equally impossible so long as the classes, with the privileges they conferred, remained in full vitality. The _jura conjugialia_, which appertained to these classes, were the dead weight upon the Kamilaroi, without emancipation from which they would have remained for additional thousands of years in the same condition, substantially, in which they were found.