Comment: 27 pages including appendices, 1 figure, 44 equationsThe observed proportionality between nominal prices and average embodied energies cannot be interpreted with conventional economic theory. A model is presented that places energy transfers as the focal point of scarcity based on the idea that (1) goods are material rearrangements, and (2) humans can only rearrange matter with energy transfers. Modified consumer and producer problems for an autarkic agent show that the opportunity cost of goods are given by their marginal energy transfers, which depend on subjective and objective factors (e.g. consumer preferences and direct energy transfers). Allowing for exchange and under perfect competition, nominal prices arise as social manifestations of goods' marginal energy transfers. The proportionality between nominal prices and average embodied energy follows given the relation between the latter and marginal energy transfers.