Axiomatization may also give ready answers to new questions when a novel interpretation of primitive concepts is discovered. As an illustration, consider the concept of a commodity, which had meant traditionally a good or a service whose physical properties and whose delivery date and location are specified. In the case of an uncertain environment, Arrow (1953) added to those characteristics of a commodity the event in which delivery will take place. In this manner one obtains, without any change in the form of the model, a theory of uncertainty in which all the results of the theory of certainty are available (Debreu [1959], Chapter 7).