...for, though the instinct to fight and to kill is surely qualified by one's personal courage, the instinct to watch others fight and kill is evidently inborn. When the boxing fan shouts, 'Kill him! Kill him!' he is betraying no peculiar pathology or quirk but asserting his common humanity and his kinship, however distant, with the thousands upon thousands of spectators who crowded into the Roman amphitheaters to see gladiators fight to the death.