43 Development of the individual necessarily entails a joint effort for the development of the human race as a whole. At Bombay We said: "Man must meet man, nation must meet nation, as brothers and sisters, as children of God. In this mutual understanding and friendship, in this sacred communion, we must also begin to work together to build the common future of the human race." (47) We also urge men to explore concrete and practicable ways of organizing and coordinating their efforts, so that available resources might be shared with others; in this way genuine bonds between nations might be forged.
Source: Populorum Progressio (Vatican.va)