The letter is one of the first magisterial documents to mention explicitly the topic of the preservation of environment. Emphasising the ecclesial doctrine to which the goods of the Earth are dedicated to all people (no. 43), Paul VI criticizes the modern practices of exploiting nature. Each property, including the gifts of nature, stands under the principle of the common use "(usus communis)", from which no human being must be excluded, the encyclical says. Unlike Leo XIII’s encyclical "Rerum novarum", Paul VI extends this postulate also on the natural environment and stresses the responsibility for future generations (no. 47). Thereby, "Octogesima adveniens" anticipates central motifs of the sustainability principle.