Pope John XXIII
Mater et Magistra §201
Mater et Magistra: On Christianity and Social Progress
201 As a rule no single commonwealth has sufficient resources at its command to solve the more important scientific, technical, economic, social, political and cultural problems which confront it at the present time. These problems are necessarily the concern of a whole group of nations, and possibly of the whole world.
Source: Mater et Magistra (Vatican.va)