It is therefore probable that the idea of murder is a prerogative of the human race, or that the human race is the only one which has arrived at the conception with great clearness, and that this superiority in man is a characteristic which differentiates him from all the other species of animals. Probably it was in this direction that, at a very early period, in the first beginnings of human life, and in that variety from which Homo sapiens emerged by selection, the intellectual force of the human species was directed, and that the comprehension of the difference between the state of life and the state of death, with the perception of the fact that living creatures might be made through certain co-ordinate actions to pass from the first state to the second, was one of the first and grandest discoveries of the human race. It is easy indeed to understand of what great use this discovery was to man in his struggle with animals physically superior to himself, to find himself in possession of the grand secret of life and death. The work of selection accomplished by man among the enemies of his species thus became systematic; it became, notwithstanding the physical feebleness of man's constitution, infinitely more efficacious than the destruction effected by man's foes, who were so much stronger, in the ranks of the human race. Governed and regulated by the clear idea of killing, with deliberate artifice, the enemies of the human race, this selection not only became a terrible weapon and assured victory to man in the struggle for existence, but it impelled him to perfect indefinitely those means of slaughter to which he owed his victory.
This discovery has been of such capital importance that one might say that the idea of killing and being killed is the fundamental idea underlying the mental system of the most savage human races—those that are nearest akin to animals—such as the Australian aborigines, the Botocudos, and the American Indians. It is well known that the savage races suffer from a perfect delirium of persecution, as witness their continual slaughter through some subtle invention of other men. The Australians even have no idea of natural death—can not conceive of a man's dying from any other than a violent cause; they believe that every one who dies has been killed by some hidden agency of destruction, just as he may have laid one low with an arrow. Hence the well-known Australian custom that, on the death of a member of the tribe, a relative must seek out some member of another tribe and kill him to revenge the supposed murder. Superstitions and cruel practices of primitive life, such as we find among the Australians, have their origin in the abuse of generalization from the one primitive discovery that one man has power over the life of another man, and one of the first mental efforts of humanity has lain in connecting these two general extensions of an idea which
