Locke believed that man was born free, and that he entered into a social contract for the purpose of protecting his person and his property. The only proper government, then, was one which, first, recognized its proper origins, i.e., a decision made by free people, and one which fulfilled its role of protecting property. It followed that governments could not arbitrarily take a person's property without their consent. Property, Locke argued, was the raison d'etre of civil society. He defined it with much more precision than would Rousseau, claiming that property was given to all by God, but that a person claimed property as his own by investing their labor in it:
Though the earth, and all inferior creatures, be common to all men, yet every man has a property in his own person: this no body has any right to but himself. The labour of his body, and the work of his hands, we may say, are properly his. Whatsoever then he removes out of the state that nature hath provided, and left it in, he hath mixed his labour with, and joined to it something that is his own, and thereby makes it his property.
Rousseau argued that the moment when man began to claim property as his own was the moment when he began to become depraved and corrupt, fallen from the state of nature. He agreed with Locke that private property was the foundation of civil society, but he viewed this as an unhealthy development for mankind. Property, he claimed in Discourse on the Origins of Inequality, was the very foundation of inequality, and, it might be said, the root of all evil, and Rousseau argued that a true savior would have said to the first person who claimed a piece of property as their own:
Be sure not to this imposter; you are lost, if you forget that the fruits of the earth belong to us all, and the earth itself to nobody.
The social contract was indeed founded in part to protect property, but this is a fundamentally bad thing. It should be noted, however, that Rousseau's views on property were at their most negative in Discourse on the Origins of Inequality. He softened his views on property in later works, including The Social Contract, which treats property in much the same way as did Locke.