For many years a tutor in the Cavendish family, Hobbes took great interest in mathematics, physics, and the contemporary rationalism. On journeys to the Continent he established friendly relations with many learned men, including Galileo and Gassendi. In 1640, after his political writings had brought him into disfavor with the parliamentarians, he went to France (where he was tutor to the exiled Prince Charles). His work, however, aroused the antagonism of the English group in France, and his thorough materialism offended the churchmen, so that in 1651 he felt impelled to return to England, where he was able to live peacefully. In the Leviathan, Hobbes developed his political philosophy. He argued from a mechanistic view that life is simply the motions of the organism and that man is by nature a selfishly individualistic animal at constant war with all other men. In a state of nature, men are equal in their self-seeking and live out lives which are "nasty, brutish, and short." Fear of violent death is the principal motive which causes men 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 a challenge to the doctrine of the divine right of kingsthe sovereign's power is absolute and not subject to the law. Temporal power is also always superior to ecclesiastical power. Though Hobbes favored a monarchy as the most efficient form of sovereignty, his theory could apply equally well to king or parliament. With these accomplishments he goes down in history as a great Philosopher.