According to Mr. Morgan,[316] the gens came into being upon three principal conceptions, the bond of kin, a pure lineage through descent in the female line, and non-intermarriage in the gens. Leaving out of view for the present the question of descent, the other conceptions give rise to obligations of great importance. The bond of kin assumes the positive obligation of mutual help, defence, and redress of injuries among the members of the gens; while the third conception implies the negative obligation which prevents the intermarriage of persons belonging to a common totem. The negative obligation is, however, no less than the positive obligation, based on the conception of kinship, and the totem device of the gens is, therefore, well described as the badge of a fraternal group. The obligation of mutual aid and defence implies the co-relative duty of doing nothing to injure a fellow member of the gens, in accordance with which all individuals of the same totem must treat each other as brethren. This applies not only to human beings, but also to the totem objects, although these may be killed and eaten by persons not belonging to the fraternal group, by which they are regarded as sacred. Sir George Grey says,[317] in relation to the _kobongs_ or totems of the Western Australians, “a certain mysterious connection exists between the family and its kobong, so that a member of the family will never kill an animal of the species to which his kobong belongs, should he find it asleep; indeed, he always kills it reluctantly, and never without affording it a chance of escape.” He adds: “This arises from the family belief, that some one individual of the species is their nearest friend, to kill whom would be a great crime, and to be carefully avoided. Similarly a native who has a vegetable for his kobong may not gather it under certain circumstances, and at a particular period of the year.” So, also, the aborigines of North America will not hunt, kill, or eat any animal of the form of their own totem.