The attainment of the common good is the sole reason for the existence of civil authorities. In working for the common good, therefore, the authorities must obviously respect its nature, and at the same time adjust their legislation to meet the requirements of the given situation .37Cf. Pius XII's broadcast message, Christmas 1942, AAS 35 (1943) 13, and Leo XIII's encyclical epistle Immortale Dei, Acta Leonis XIII, V, 1885, p. 120.
Among the essential elements of the common good one must certainly include the various characteristics distinctive of each individual people. 38Cf. Pius XII's encyclical letter Summi Pontificatus, AAS 31 (1939) 412-453. But these by no means constitute the whole of it. For the common good, since it is intimately bound up with human nature, can never exist fully and completely unless the human person is taken into account at all times. Thus, attention must be paid to the basic nature of the common good and what it is that brings it about. 39Cf. Pius XI's encyclical Mit brennender Sorge, AAS 29 (1937) 159, and his encyclical letter Divini Redemptoris, AAS 29 (1937) 65-106.