Summi Pontificatus §58

⁵⁸ Indeed, as Our great predecessor, Leo XIII, wisely taught in the Encyclical Immortale Dei, it was the Creator's will that civil sovereignty should regulate social life after the dictates of an order changeless in its universal principles; should facilitate the attainment in the temporal order, by individuals, of physical, intellectual and moral perfection; and should aid them to reach their supernatural end.