To speak less learnedly, and more intelligibly, - John Locke

God planted in men a strong desire also of propagating their kind, and continuing themselves in their posterity; and this gives children a title to share in the property of their parents, and a right to inherit their possessions.

The measure of property nature has well set by the extent of men's labour and the conveniencies of life: no man's labour could subdue, or appropriate all; nor could his enjoyment consume more than a small part; so that it was impossible for any man, this way, to intrench upon the right of another, or acquire to himself a property, to the prejudice of his neighbour, who would still have room for as good and as large a possession (after the other had taken out his) as before it was appropriated.

This makes it Lawful for a Man to Kill a Thief, who has not in the least hurt him, nor declared any design upon his life, any farther then by the use of Force, so to get him in his Power, as to take away his Money, or what he pleases from him.: because using force, where he has no Right, to get me into his Power, let his pretense be what it will, I have no reason to purpose that he, who would take away my Liberty, would not when he had me in his Power, take away every thing else. And therefore it is Lawful for me to treat him, as one who has put himself into a State of War with me, I.e. kill him if I can; for to that hazard does he justly expose himself, whoever introduces a State of War, and is Aggressor in it.