The duel is in substance a more or less deliberate resort to a fight as a final settlement of a difference of opinion.

In civilized communities it prevails as a normal phenomenon only where there is an hereditary leisure class, and almost exclusively among that class.

The exceptions are (1) military and naval officers who are ordinarily members of the leisure class, and who are at the same time specially trained to predatory habits of mind and (2) the lower-class delinquents--who are by inheritance, or training, or both, of a similarly predatory disposition and habit.

It is only the high-bred gentleman and the rowdy that normally resort to blows as the universal solvent of differences of opinion.

The plain man will ordinarily fight only when excessive momentary irritation or alcoholic exaltation act to inhibit the more complex habits of response to the stimuli that make for provocation.