It is widely acknowledged that most social reformers or utopians of the early nineteenth century, with few exceptions, contributed to sidelining environmental concerns in favor of the ideals of progress and perfectibility they championed. This is particularly true of Saint-Simon and his followers, who are often seen as advocates of an industrialist philosophy and a Promethean domination of nature, which has influenced economic growth up to the present day. However, the underlying principles of the Saint-Simonian stance are seldom analyzed in detail, and this position is sometimes unfairly contrasted with modern concepts of environmental economics. This chapter explores Saint-Simon’s naturalistic philosophy, which views human activity as an extension of nature rather than a force in opposition to it. While advocating an industrial system, this regime is seen as temporary, bound by a broader geological timeline. The work of Saint-Simon’s disciples, particularly from 1825 to 1832, formalized the link between “total exploitation of the Earth” and the end of “exploitation of man by man”, distancing itself from the cosmology of Saint-Simon. Their focus shifts from a naturalist philosophy to a historical philosophy that is both teleological and optimistic. The religious evolution of the Saint-Simonian school did not alter this trajectory, in which the industrial transformation of the earth, water, and air was seen as having no uncontrollable negative effects on nature or humanity.