 Perhaps the most central concept in Locke’s political philosophy is his theory of natural law and natural rights. The natural law concept existed long before Locke as a way of expressing the idea that there were certain moral truths that applied to all people, regardless of the particular place where they lived or the agreements they had made. The most important early contrast was between laws that were by nature, and thus generally applicable, and those that were conventional and operated only in those places where the particular convention had been established. This distinction is sometimes formulated as the difference between natural law and positive law.