Whatever the actual lifetimes of individual

reserves might be, and they could vary considerably,

the point remains; if present trends continue; if they

do and technology cannot meet the demands made on it,

the question of resource exhaustion becomes not if,

but when. But current trends may not continue, and

therein lies the principal weakness of both studies.

 It is in keeping with what we have so often said

in this manuscript that both the Club of Rome and

Barnett and Morse' studies have given numbers a reality

all their own. Yet, while numbers reflect economic

activity, they are not themselves the activity; they

result from it. The activities they describe are

separate, real, physical phenomena. What factors

caused economic growth to occur in the recent past and

which were most important cannot be determined with

certainty; quite definitely they cannot be expressed

in a number. Growth results essentially from qualitative,

not quantitative change. What we do know is that the

growth that resulted, insofar as it represented an

increased volume of output of metals, represented

extraction. Neither production nor growth in production

can be viewed as a separate phenomenon from extraction.

 As the different results of the two studies show,

whether future growth (in the same sense) can continue

at the same rate depends upon technology; now whether