Epicurus on his part at least proceeded more consistently in accord with his sensual system (for in his inferences he never exceeded the bounds of experience) than Aristotle and Locke (especially, however, the latter), who, after he had derived all concepts and principles from experience, goes so far in their use as to assert that one can prove the existence of God and the im mortality of the soul (though both objects lie entirely outside of the bounds of possible experience) just as self evidently as any mathematical theoremY.