" So the first biological lesson of history is that life is competition. Competition is not only the life of trade, it is the trade of life—peaceful when food abounds, violent when the mouths outrun the food. Animals eat one another without qualm; civilized men consume one another by due process of law. Co-operation is real, and increases with social development, but mostly because it is a tool and form of competition; we co-operate in our group—our family, community, club, church, party, “race,” or nation—in order to strengthen our group in its competition with other groups. Competing groups have the qualities of competing individuals: acquisitiveness, pugnacity, partisanship, pride. Our states, being ourselves multiplied, are what we are; they write our natures in bolder type, and do our good and evil on an elephantine scale. We are acquisitive, greedy, and pugnacious because our blood remembers millenniums through which our forebears had to chase and fight and kill in order to survive, and had to eat to their gastric capacity for fear they should not soon capture another feast. War is a nation’s way of eating. It promotes co-operation because it is the ultimate form of competition. Until our states become members of a large and effectively protective group they will continue to act like individuals and families in the hunting stage. "
― Will Durant , The Lessons of History