On the origin of the concept of natural monopoly

This article contributes to the history of the concept of natural monopoly, focusing on the reconstruction of its origins. It considers natural monopoly as composed of different elements: 1. the expression itself; 2. the singling out of the concrete situations to which it is applied; 3. the inquiry into economies of scale; 4. the consideration of their incompatibility with perfect competition; 5. the drawing of the diagram; 6. the need for government intervention. In the paper each of the above feature is separately examined from a historical perspective. Priorities and influences are then traced, in particular it is found that the pivotal figure in this historical reconstruction is that of Edgeworth. It is also highlighted the relation of the concept of natural monopoly with that of competition, as well as its policy implications