Social contract theory is one of the key areas of political thought and political philosophy. It is the notion that legitimate government is the artificial product of the voluntary agreement of free moral agents rather than a consequence of "natural" political authority; or as Locke asserted, "voluntary agreement gives political power to governors." Michael Lessnoff"s collection of readings includes extracts both from the work of the great contractarian philosophers such as Hobbes, Locke, and Rousseau and from more recent writers such as Rawls and Gauthier.