Hobbes developed a materialist and highly pessimistic philosophy that was denounced in his own day and later, but has had a continuing influence on Western political thought. His Leviathan (1651) presents a bleak picture of human beings in the state of nature, where life is "nasty, brutish, and short." Fear of violent death is the principal motive that causes people to create a state by contracting to surrender their natural rights and to submit to the absolute authority of a sovereign. Although the power of the sovereign derived originally from the people, Hobbes said-challenging the doctrine of the divine right of kings-the sovereign's power is absolute and not subject to review by either subjects or ecclesiastical powers. Hobbes's concept of the social contract led to investigations by other political theorists, notably Locke, Spinoza, and Rousseau, who formulated their own radically different theories of the social contract.