From The End of Modernity by Thaddeus Kozinski:
According to St. Thomas, men cannot adequately understand in theory, let alone fulfill in practice, the detailed precepts of the natural law without the help of its author, God, and its divinely appointed interpreter, the Roman Catholic Church. With regard to a non-sacral foundation for political order, the Thomist Joseph May in the 1950s stated: “The only true doctrine is that civil society cannot prescind from the ultimate end [emphasis mine] both because the temporal welfare implies an ordering to the spiritual and supernatural, and because the individual citizens are directly and positively bound to tend to it.” And even Dignitatis Humanae insists that it “leaves untouched the traditional Catholic doctrine about the moral duty of men and societies toward the true religion and the one Church of Christ” (Sec. 1). As Pope John Paul II often reiterated, the face of Jesus Christ is the only true mirror in which man can fully and accurately contemplate and comprehend his own nature and destiny; thus, only therein can he discern the moral values and goods most perfective of himself and the political order.