But if there be any occasion on which it is proper to slay a man,—and there are many such,—surely that occasion is not only a just one, but even a necessary one, when violence is offered, and can only be repelled by violence. When a military tribune offered violence to a soldier in the army of Caius Marius, the kinsman of that commander was slain by the man whom he was insulting; for the virtuous youth chose to act though with danger, rather than to suffer infamously; and his illustrious commander acquitted him of all guilt, and treated him well. [10] But what death can be unjust when inflicted on a secret plotter and robber?