If we can admit the argument as to the sequence of incidents which thus led to the primary amicable conjunction of two males within the same group, it is not necessary to enter very minutely into the exact manner in which it would grow into a habit and spread throughout the land. We may surmise that, in spite of the advantages presented, its progress would, from the isolation of the groups, and their mutual hostility, be very slow. This would specially be the case if, as with physical variations, this point of departure in social development was a purely individual one, and so had to spread from a single centre by natural selection acting through a beneficial variation. It is, in fact, difficult to conceive, in view of the series of the abnormal factors we have supposed necessary for the genesis of such evolution, that any coincident departure of the same nature would be likely to occur in any other centre. It is even certain that the full possible benefit of the innovation would not be able to make itself felt even in the group of its creators. It is easy to understand that, in spite of the shield-like love of the mother, there would be friction between father and son in such unfamiliar circumstances, not only novel to the individual, but unhabitual to the race. In fact, it may be taken for granted that on the part of the father there was at first only a sulky tolerance of the new arrangement, a tacit but very unwilling acquiescence in the presence of the son. On the part of the son would exist a watchful reserve, with an ever-haunting sense of insecurity, born of a novel and precarious situation. Even on such terms, however, and with what little might be of conciliation between the two, it is evident that a momentous forward step has been taken: the powers of the group in offence and defence, as against outsiders, would be enormously increased;[1] the fire of youth and the wisdom of old age for the first time joined forces, and paternal experience comes to the aid of filial courage and ardour. On the death of the patriarch the family found a natural protector, and what potential germs of advance, material or spiritual, had been evolved, would remain intact.