Harold Hotelling’s 1931 article on the economics of exhaustible resources is considered groundbreaking in the history of non-renewable resource analysis. Hotelling’s innovation has been characterized by comparing his work with other contributions dealing with conservation issues. It has also been connected to his earlier work on depreciation, published in 1925, for using the same kind of mathematical formalism. This paper further explores this second research direction on the basis of new archival materials, showing that Hotelling conceived his contributions on resources and depreciation as closely and substantially intertwined. It also suggests that Hotelling’s interest in exhaustible resources came from his earlier readings in accounting. These results shed new light on Hotelling’s early economic research, on our common understanding of his 1931 contribution, and on the origins of the connection between nature and capital in the history of environmental economics.