Without recognising indivisibilities — in human person, in residences, plants, equipment, and in transportation — location patterns, down to those of… - Tjalling Koopmans

Decisions and plans made by others... [can be judged to be] quantitatively at least as important as the primary uncertainty arising from random acts of nature and unpredictable changes in consumers' preferences.

One can in particular interpret the proposition as a statement conditions under which the simplicity of incentive structure and the economies of information handling characteristic of a competitive market organization can be secured without loss of efficiency of allocation... The price system carries to each producer, resource holder, or consumer a summary of information about the production possibilities, resource availabilities and preferences of all other decision makers. Under the conditions postulated, this summary is all that is needed to keep all decision makers reconciled with a Pareto optimal state once it has been established.

We look upon economic theory as a sequence of conceptual models that seek to express in simplified form different aspects of an always more complicated reality.