However, in the 17th century writers like Pierre Bayle, John Locke, Richard Overton and Roger William broke the link between territory and faith, which eventually resulted in a shift from territoriality to religious voluntarism. It was Locke who, in his Letter Concerning Toleration, defined the state in purely secular terms: "The commonwealth seems to me to be a society of men constituted only for the procuring, preserving, and advancing their own civil interests." Concerning the church, he went on: "A church, then, I take to be a voluntary society of men, joining themselves together of their own accord." With this treatise, John Locke laid one of the most important intellectual foundations of the separation of church and state, which ultimately led to the secular state.