The preceding chapters may strike the reader as reflecting an underlying mood of unwarranted technological optimism. Certainly they lack the apocalyptic vision (or, at the very least, the obligatory lugubrious tone) which has come to dominate the recent discussion of man's present estate and his future economic prospects. This seems an appropriate opportunity, therefore, for linking some of the themes of this volume to present-day concerns, especially our preoccupation with the supposed inadequacy of our natural-resource base for sustaining continued economic growth and the prospective contribution of science to such growth.

My starting point is that the potential flexibility and adaptability of advanced industrial economies is vastly underestimated. This is particularly the case with respect to dependence upon specific natural-resource inputs. Most thinking about the role of natural resources in economic growth continues to be excessively static. It ignores not only the dynamic interactions between technological change and natural resources, but also the whole range of additional adaptations which are a mixture of pure technological change, redesigning, and substitution. Thus rising fossil-fuel prices may eventually lead to the more rapid development of techniques for the exploitation of atomic or solar energy, but they will doubtless also lead to the utilization of lower-quality oil sources, to the redesign and modification of automobile engines, and to the use of more blankets, insulating material, and thermal underwear. It is even conceivable that the influx of people into Florida and southern California will grow. The point is not that, therefore, the increasing scarcity of fossil fuels is of no consequence. That would be patently absurd. Rising fuel costs have very widespread ramifications.