p. 259
We must devote our attention first of all to that order which should prevail among men.
Any well-regulated and productive association of men in society demands the acceptance of one fundamental principle: that each individual man is truly a person. His is a nature, that is, endowed with intelligence and free will. As such he has rights and duties, which together flow as a direct consequence from his nature. These rights and duties are universal and inviolable, and therefore altogether inalienable. 7Cf. Pius XII's broadcast message, Christmas 1942, AAS 35 (1943) 9-24; and John XXIII's sermon, Jan. 4, 1963, AAS 55 (1963) 89-91.