Jan Tinbergen was a brilliant scientist, but he was also always available if the society called upon him. The government asked his help in designing macroeconomic policy in the post-war reconstruction of the Netherlands. However, soon he realized that the main problems in the world were poverty, war and the environment. Justice and good governance were the key in his thinking. Gradually the environment became his main concern. He has written two books, in Dutch: “Een Leefbare Aarde” (“A Livable Earth”) in 1970, and “Kunnen Wij de Aarde Beheren?” (“Can We Manage the Earth?”) in 1987. The first book is mainly about poverty and development but at the end, it touches upon the environment. In the second book, the environment has taken a prominent place. In this article, I will summarize what Jan Tinbergen has put forward in these books, in order to characterize the importance of his thinking and his contributions.