"The slippery role of information as an economic good is of deep significance to economic behavior, especially in the relatively information-rich modern economy. It is an economic good in the traditional sense; it is valuable, and it is costly. But it has a peculiar algebra. Adding one ton of steel to another permits more to be done; repeating the same item of information does not add anything useful. On the other hand, supplying a ton of steel to another reduces the steel available to the supplier; supplying information to another does not reduce the information available to the supplier."