80 THE ANATOMY OF SCIENCE 



. . . even when men ^^'ere coming extraordinarily near to what we 

 should call the truth about local motion, they did not clinch the 

 matter— the thing did not come out clear and clean— until tliey had 

 realized and had made completely conscious to themselves the fact 

 that they were in reality transposing the question into a different 

 realm— they were discussing not real bodies as we actually obsei"ve 

 them in the real world, but geometrical bodies moving in a world 

 without resistance and without gravity— moving in that boundless 

 emptiness of Euclidean space which Aristotle had regarded as un- 

 thinkable. 



And now arises the crucial question— posed, and answered, by Hall 

 as follows : 



When abstraction has played its part, when attention has been 

 given to the really existing physical properties of bodies, when the 

 mathematization of the phenomena has been fully explored and a 

 theoretical science begins to take shape, how is the investigator to 

 determine whether his image or model of things in the abstracted uni- 

 verse represents faithfully things as they are according to experience? 

 Galileo's answer to this problem, prepared for him by earlier logicians, 

 was the appeal to experiment. If theoretical examination suggests that 

 in specified conditions the event B will follow the event A, then the 

 reasoning can be tested by creating those conditions, and making the 

 observation. 



By analysis of a collection of \'aried obsers^ations and experiments, 

 Bacon supposed, the scientist strips away successive veils of decep- 

 tive appearance to arrive, at last, at a hard core of secure knowledge. 

 Stripping away, one by one, the concentric coats of an onion, we so 

 arrive at last at its center. This metaphor itself suggests the inade- 

 quacy of the Baconian conce^Dtion: working entirely from the outside, 

 detachment of the onion's smooth and tenacious shells is very diffi- 

 cult. We succeed precisely when, penetrating with knife or finger- 

 nail, we secure the purchase with which we detach the coat by break- 

 ing outward, toward the surface. The successful technique in the 

 metaphor suggests the quadripartite scientific method pioneered by 

 Galileo ( and Archimedes ) : 



( 1 ) Resolving to study "falling bodies," the scientist finds that he 

 can hold simultaneously in view very few unrelated elements of ex- 

 perience. Quite early in his enterprise he must then devise a body of 



