Science naively presupposes the intelligibility of the universe, necessary laws, and a universal truth. The author reflects on these presuppositions to arrive at a demonstration of God's existence. In a vigorous and exclamatory style, he condemns the alternative views of idealism, phenomenology, and philosophies of science which cannot rationally justify their faith in a universal truth. The only rational basis for these presuppositions is a theistic God--the "Vérité mesurante" and "Pensée fondatrice" of scientific reason.--A. B. D.