From Journal of a Novel: the East of Eden Letters:
The two oldest and strongest children of ego are domination and possessiveness.
And the youngest and stupidest child is desire for immortality.
Another offspring is competitiveness, which is a desire to prove superiority.
I had an epiphany after reading this. Human behavior that left me perplexed now makes perfect sense. I also realize that it wouldn't be a bad thing for me to trade some ego for humility.