ABSTRACT
Tweedledum and Tweedledee are twins whose talents for production and preferences for consumption are equal but opposite. Exchange is the key to greater productivity. By enabling each brother to consume what the other produces, it makes possible the "division of labour". As long as the rate of exchange is between the fairly wide limits, trade is to their mutual advantage. Tweedledee faces exactly the same choices as Tweedledum. The assumption that preferences can be expressed as proportions of total resources is purely for the sake of simplicity. These proportions are used to illustrate the effects of different types of change. More realistic assumptions would merely add complexity without affecting the principle. Trade is obviously a good thing for both Tweedledum and Tweedledee. The opportunity for exchange is the equivalent of a threefold increase in their productivity.
