Nothing is to be accounted hostile force but where it leaves
not the remedy of such an appeal [to the law], and it is such
force alone that puts him that uses it into a state of war,
and makes it lawful to resist him.

A man with a sword in his hand demands my purse on the
highway, when perhaps I have not 12 pennies in my pocket.

This man I may lawfully kill.

To another I deliver 100 pounds to hold only whilst I alight,
which he refuses to restore to me when I am got up again,
but draws his sword to defend the possession of it by force.
I endeavour to retake it.

The mischief this man does me is a hundred, or possibly
a thousand times more than the other perhaps intended
me (whom I killed before he really did me any); and yet
I might lawfully kill the one and cannot so much as hurt
the other lawfully.

The reason whereof is plain to see; because the one using
force which threatened my life, I could not have time to
appeal to the law to secure it, and when it was gone it
was too late to appeal.

The law could not restore life to my dead carcass.

The loss was irreparable; which to prevent, the law of
Nature gave me a right to destroy him who had put himself
into a state of war with me and threatened my destruction.

But in the other case, my life not being in danger, I might
have the benefit of appealing to the law, and have reparation
for my 100 pounds in that way.

-- John Locke, "An Essay Concerning the True Original Extent
   and End of Civil Government", Chapter 18 "Of Tyranny",
   #207, originally published in England, 1690.
