“But if wealth generated by such ‘rearrangements’ bewildered folk, the information-searching activities of tradesmen evoked truly great distrust. The transport involved in trade can usually be at least partly understood by the layman, at least after some patient explanation and argument, to be productive. For example, the view that trade only shifts about already existing things can be readily corrected by pointing out that many things can be made only by assembling substances from widely distant places. The relative value of these substances will depend not on the attributes of the individual material components of which they consist but on relative quantities available together at the locations required. Thus trade in raw materials and semi-finished products is a precondition for increase in the physical quantities of many final products that could only be manufactured at all thanks to the availability of (perhaps small quantities of) materials fetched from far away. The quantity of a particular product that can be produced from resources found at a particular place may depend on the availability of a very much smaller quantity of another substance (such as mercury or phosphor, or perhaps even a catalyst) that can be obtained only at the other end of the earth. Trade thus creates the very possibility of physical production. The idea that such productivity, and even such bringing together of supplies, also depends on a continuous successful search for widely dispersed and constantly changing information remains harder to grasp, however obvious it may seem to those who have understood the process by which trade creates and guides physical production when steered by information about the relative scarcity of different things at different places.”