A state according to St. Thomas is a part of the universal empire of which God is the maker and ruler. Its laws are, or can be made to be, particular determinations of this empires eternal code, and the authority which enforces these laws is a power whose origin is also in God. Its goal and justification is to offer to man satisfactory material conditions of life as a basis for a moral and intellectual education which, in turn, must be such as to lend itself to the spiritual edification of the Christian man. St. Thomas follows the Aristotelian doctrine that makes of man a political animal, but he modifies it in accordance with the exigencies of his Christian philosophy. The fact that man operates, not by instinct, but by reason makes social organization indispensable. The interdependence of reason and sociability is explained by St. Thomas as follows: by endowing man with reason and at the same time depriving him of instinct and of an available ready made supply of the necessities of life, God decreed that man should be a political animal.