Theory of Changes of Normal Demand and Supply in Relation to the Doctrine of Maximum Satisfaction

In earlier chapters of this Book, and especially in chapter xii., we have considered gradual changes in the adjustment of demand and supply. But any great and lasting change in fashion; any substantive new invention; any diminution of population by war or pestilence; or the development or dwindling away of a source of supply of the commodity in question, or of a raw material used in it, or of another commodity which is a rival and possible substitute for it:—such a change as any of these may cause the prices set against any given annual (or daily) consumption and production of the commodity to cease to be its normal demand and supply prices for that volume of consumption and production; or, in other words, they may render it necessary to make out a new demand schedule or a new supply schedule, or both of them. We proceed to study the problems thus suggested.