Populorum Progressio §17

¹⁷ Each man is also a member of society; hence he belongs to the community of man. It is not just certain individuals but all men who are called to further the development of human society as a whole. Civilizations spring up, flourish and die. As the waves of the sea gradually creep farther and farther in along the shoreline, so the human race inches its way forward through history. We are the heirs of earlier generations, and we reap benefits from the efforts of our contemporaries; we are under obligation to all men. Therefore we cannot disregard the welfare of those who will come after us to increase the human family. The reality of human solidarity brings us not only benefits but also obligations.