The cause lies deeper than that.

It rests in the willingness or desire of the murderer to kill at all.

Among barbaric or savage peoples this is natural; but among civilized nations it is hardly to be anticipated.

If the negro who shoots his fellow because he believes himself to have been cheated out of ten cents were really civilized, he would either not have the impulse to kill or, having the impulse to kill, would have sufficient power of self-control to refrain from doing so.

This power of self-control may be natural or acquired, and it may or may not be possessed by the man who feels a desire to commit a homicide.