Hobbes's theories decisively shape the concept of sovereignty through the medium of social contract theories. Jean-Jacques Rousseau's (1712–1778) definition of popular sovereignty (with early antecedents in Francisco Suárez's theory of the origin of power), provides that the people are the legitimate sovereign. Rousseau considered sovereignty to be inalienable; he condemned the distinction between the origin and the exercise of sovereignty, a distinction upon which constitutional monarchy or representative democracy is founded. John Locke, and Montesquieu are also key figures in the unfolding of the concept of sovereignty; their views differ with Rousseau and with Hobbes on this issue of alienability.