After having been a key figure of the new “realist” generation in the 1930s, a noted pen of the Doriotist press until Munich and a liberal theorist of power and sovereignty, (particularly hailed outside of France), in the aftermath of the second world war, Bertrand de Jouvenel expanded the scope of his work to become a leading pioneer of environmentalism at the end of the 1950s. He published Arcadie, an essay, in 1968. This article includes three parts: the roots of Jouvenel’s environmentalism (the legacy of Colette, the 1930 generation and Anglo-Saxon influences), its content and specificities (emphasis on economics and on the role of experts), and finally an interpretation of the itinerary of the author who proclaimed himself a “'traveler through the century.”'