A man with a sword in his hand demands my purse in the high-way, when perhaps I have not twelve pence 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 me, when I am got up again, but draws his sword to defend the possession of it by force, if 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; 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.