The achievements which dispelled our fears of the cosmos took place three centuries ago. What additional roles has the scientific understanding of the 19th and 20th centuries played? In the physical sciences, these achievements concern electricity, chemistry, and atomic physics. In the life sciences, there has been an enormous increase in our understanding of disease, in the mechanisms of heredity, and in bio -- and physiological chemistry. The major effect of these advances appears to lie in the part they have played in the industrial revolution and in the tools which scientific understanding has given us to build and manipulate a more protective environment. In addition, our way of dealing directly with natural phenomena has also changed. Even in domains where detailed and predictive understanding is still lacking, but where some explanations are possible, as with lightning and weather and earthquakes, the appropriate kind of human action has been more adequately indicated.

Apparently the population as a whole eventually acquires enough confidence in the explanations of the scientists to modify its procedures and its fears. How and why this process occurs would provide an interesting separate subject for study. In some areas, the progress is slower than in others. In agriculture, for example, despite the advances in biology, elaborate rituals tend to persist along with a continued sense of the imminence of some natural disaster. In child care, the opposite extreme prevails; procedures change rapidly and parental confidence probably exceeds anything warranted by established psychological theory. There are many domains in which understanding has brought about widespread and quite appropriate reduction in ritual and fear. Much of the former extreme uneasiness associated with visions and hallucinations and with death has disappeared. The persistent horror of having a malformed child has, I believe, been reduced, not because we have gained any control over this misfortune, but precisely because we have learned that we have so little control over it. In fact, the recent warnings about the use of X-rays have introduced fears and ambiguities of action which now require more detailed understanding, and thus in this instance, science has momentarily aggravated our fears. In fact, insofar as science generates any fear, it stems not so much from scientific prowess and gadgets but from the fact that new unanswered questions arise, which, until they are understood, create uncertainty.