The social progress, order, security and peace of each country are necessarily connected with the social progress, order, security and peace of all other countries.

This line reflects Pope John XXIII’s teaching during the early 1960s, when the Cold War and the threat of nuclear conflict made questions of international order and peace urgent. In his social encyclical *Pacem in Terris* (1963), issued shortly after the Cuban Missile Crisis, John XXIII argued that modern interdependence had made purely national solutions inadequate: the well-being and stability of any one nation increasingly depended on the well-being and stability of others. The statement belongs to his broader appeal for a moral framework for international relations grounded in human rights, justice, and cooperation among states.

The quotation asserts a principle of global interdependence: a nation’s internal flourishing—its social development, public order, safety, and peace—cannot be isolated from the conditions of the wider world. John XXIII is rejecting a narrow nationalism that treats peace as a domestic achievement or a matter of deterrence alone. Instead, he implies that peace is systemic: insecurity, injustice, or disorder in one place tends to spill across borders, while genuine progress and stability are mutually reinforcing. The line also carries a moral claim: because nations are linked, they bear responsibilities toward one another, making international cooperation and institutions not optional but necessary for lasting peace.