Whichever theory we adopt to give a rational explanation of human existence, that theory must take into account and explain the mental nature we see at work in all modern communities.
The discovery of agriculture was the first big step toward a civilized life.
There are the further difficulties of building a population out of a diversity of races, each at a different stage of cultural evolution, some in need of restraint, many in need of protection; everywhere a bewildering Babel of tongues.
Man is by nature competitive, combative, ambitious, jealous, envious, and vengeful.
No tribe unites with another of its own free will.