Heirs of the German Naturphilosophie, Élisée Reclus (1830-1905) and George Perkins Marsh (1801-1882), who exchanged letters and cited each other’s publications. In the mid XIXth Century they denounced the destruction of nature caused by human activities. However, their conceptions about the relationship between nature and society soon diverged. Their correspondence (1868-1871) stopped. An incompatibility emerged between the anarchist Reclus and the ambassador Marsh, Whig and Calvinist puritan. The metaphysical vision of nature held by Marsh, developing steadily in the successive editions of his Man and Nature after 1864, did not fit in with the secular ethics and practical aesthetic of Reclus. Both men shared a commonutilitarian concept of nature (to use nature for its resources and for contemplation). But the anthropocentrism of Marsh does not go beyond the superiority accorded to God. Within his social anarchism, that promoted a sharing of the benefits coming fromprogress towards all people, Reclus combined protection of landscape, respect for animal or plant species, and rationalized management of space and environments. Marsh, supporter of the State, which is the transcendental political form corresponding to monotheist religion symbolized by Calvinist puritanism, can be praised by present green parties, but not Reclus who is atheist, non-statist and supporter of social revolution.