Sergei Andreyevich Podolinsky (1850-1891), a Ukrainian socialist among the first to explicitly scrutinize the economic process from a thermodynamics perspective. Podolinsky was heavily influenced by the Physiocrats, Carnot, and Clausius. In his work, he cited the Physiocrats' emphasis on nature as the source of wealth and the economic implications of Clausius and Carnot's discoveries. Podolinsky tried to reconcile the labor theory of value with a thermodynamic analysis of the economic process. In his conclusions, which he communicated to Frederick Engels on several occasions, Podolinsky stated that the socialist model was flawed because it assumed that “scientific socialism” would overcome all natural resource scarcities and enable unlimited material expansion. Podolinsky’s biophysical analysis led him to conclude that ultimate limits to economic growth lay not in the shackles of the relations of production, but in physical and ecological laws. Podolinsky’s work and concepts are now widely used among some biophysical analysts.