104 THE ANATOMY OF SCIENCE 



the space-time map of a material system from 

 presenting a highly fibrous or stringy appear- 

 ance. Will this unsymmetrical extension with 

 respect to space and time ultimately be re- 

 garded as a flaw in that space-time geometry 

 which seems to us now so perfect? 



But I have wandered far from the main pur- 

 pose of this chapter, which was to survey the 

 growth of the science of mechanics. A diagram 

 of the sort drawn in Figure 18 displays the 

 whole of the science of dynamics with the excep- 

 tion of the law of gravitation, which in its most 

 qualitative aspect may be expressed by the state- 

 ment that the space-time paths of two bodies 

 will be curved toward one another, and the cur- 

 vature will be greater the closer their approach 

 to one another. If our diagram included the 

 paths of several bodies as in the space-time map 

 of the solar system which I presented in Figure 

 13 of the last chapter, all of these paths together 

 may be said to produce a "field" which deter- 

 mines at each point the curvature of each path. 

 Now let us introduce into the picture the path 

 of another body called a test-body, which, 

 merely for simplicity, we shall consider a comet, 

 or any other body of sufficiently small mass so 

 that its presence will not materially alter the 



