John Locke's account of natural law, which forms the very basis of his political philosophy, has troubled many critics over time. The two works that shed light on Locke's theory are the early Essays on the Law of Nature and the Second Treatise of Government, published over twenty years later. Many critics have assumed that the early work presents a voluntarist approach to natural law and the second a rationalist approach, but the present analysis shows that Locke's theory is consistent. Both works present a concept of the law of nature that must be placed between voluntarism and rationalism.