In human cohabitation, every natural right in a person implies a respective duty in all other persons.
(Encyclical Letter Pacem in terris, 11 April 1963)
Duty of every man, the Christian's compelling duty is to consider the superfluous with the measure of the needs of others, and to be very vigilant because the administration and distribution of the created goods is put to the advantage of everyone.
(Radio message to all the Christian faithful one month after the Council, 11 September 1962)
Iindividual human beings are and must be the foundation, the cause and the end of every social institution in which social life is expressed and implemented.
(Encyclical Letter Mater et Magistra, 15 May 1961)