John Locke in his Second Treatise of Government summarizes Social Contract Theory in the phrase, "Being all equal and independent, no one ought to harm another in his life, health, liberty, or possessions" (Locke 1689] 1980, 2.6). Within this statement is the argument that an individual has certain unalienable, unchanging, natural rights simply because he or she is human, which was a radical thought for the 17th century. According to Locke, outside of society there is no way of guaranteeing that these natural rights will not be transgressed. Locke suggests that human beings, however, since we are led by reason-a faculty which tells each of us to make decisions based upon self-preservation-eventually emerge from the "State of Nature" to establish laws for the very purpose of protecting against the infraction of these "Natural Rights." Political society established on the basis of Social Contract Theory, therefore, properly exists on the foundation of Natural Law, the idea that universal moral principles guide human conduct