Pacem in Terris §136

¹³⁶ Now, if one considers carefully the inner significance of the common good on the one hand, and the nature and function of public authority on the other, one cannot fail to see that there is an intrinsic connection between them. Public authority, as the means of promoting the common good in civil society, is a postulate of the moral order. But the moral order likewise requires that this authority be effective in attaining its end. Hence the civil institutions in which such authority resides, becomes operative and promotes its ends, are endowed with a certain kind of structure and efficacy: a structure and efficacy which make such institutions capable of realizing the common good by ways and means adequate to the changing historical conditions.