We do not know whether technology and good

 fortune will allow costs to remain low under the

 pressure of exponential rates of increase in demand.

 If we look only to the recent past, the outlook does

 not appear to be tco bad, but it has been our purpose

 to show that the past century is not a very good base

 from which to project future developments. All years

 are exceptional; in this matter of resources in

 America, the past century has been especially so.

 Resources probably must run low eventually if

 increased production of the kind developed during the

 past century continues; but whether the same kinds of

 production will continue is not so certain. So many

 links exist in the productive process that there may

 be no way to establish a hard and fast relationship

 between "output" and materials needs.

 In addition, new materials may be found and

applied to new uses. Vast new ore deposits may be

discovered or radical changes in technology may make

old methods of mining and concentration obsolete. New

kinds of goods and services may be developed. Any

number of things might occur to change the materials

picture in the future. But to speculate about such

developments is one thing and to count on them is

quite another. An assumption that technology, like the

hero of many novels, will forever be able to meet all

materials crises is unwarranted. Moreover, we must