"The defence of one's self, justly called the primary law of nature, is not, nor can it be abrogated by any regulation of municipal law. This principle of defence is not confined merely to the person; it extends to the liberty and the property of a man: it is not confined merely to his own person; it extends to the persons of all those, to whom he bears a peculiar relation - of his wife, of his parent, of his child, of his master, of his servant: nay, it extends to the person of every one, who is in danger; perhaps, to the liberty of every one, whose liberty is unjustly and forcibly attacked. It becomes humanity as well as justice."
Wilson, James. "Lectures on Law: Of the Natural Rights of Individuals." The Works of the Honourable James Wilson. Ed. Bird Wilson. Vol. 2. Philadelphia: Lorenzo Press, 1804. 496. Print.
This quote is found on page 65 of Proclaiming Liberty which is available from Amazon.com for $12.95. The Kindle edition is now available for $3.95.