The science of mine and thine - the science of justice - is the science of all human rights; of all a man's rights of person and property; of all his rights to life, liberty, and the pursuit of happiness.

It is the science which alone can tell any man what he can, and cannot, do; what he can, and cannot, have; what he can, and cannot, say, without infringing the rights of any other person.

It is the science of peace; and the only science of peace; since it is the science which alone can tell us on what conditions mankind can live in peace, or ought to live in peace, with each other.

These conditions are simply these: viz., first, that each man shall do, towards every other, all that justice requires him to do; as, for example, that he shall pay his debts, that he shall return borrowed or stolen property to its owner, and that he shall make reparation for any injury he may have done to the person or property of another.

The second condition is, that each man shall abstain from doing to another, anything which justice forbids him to do; as, for example, that he shall abstain from committing theft, robbery, arson, murder, or any other crime against the person or property of another.

So long as these conditions are fulfilled, men are at peace, and ought to remain at peace, with each other. But when either of these conditions is violated, men are at war. And they must necessarily remain at war until justice is re-established. - Lysander Spooner, Natural Law