4 THE LIMITATIONS OF SCIENCE 



change in method in the nineteenth century is under- 

 stood if we consider the state of scientific knowledge 

 before that time. 



Few of the properties of heat, light, sound, and 

 electricity were then known, but, on the other hand, the 

 laws of mechanics were well established, and a solid 

 foundation of experimental fact permitted a broad 

 and comprehensive application of pure mathematics to 

 that branch of physics. It is altogether natural that 

 mechanics should have developed first, for it is the only 

 part of the science which rests directly on the data of 

 experience. It considers only material bodies and their 

 sensible and common properties such as the occupa- 

 tion of space and the resistance to motion. To measure 

 properties of matter other than spatial and dynamical 

 requires more elaborate apparatus, and it is more diffi- 

 cult to separate extraneous accidents from such at- 

 tributes as color, temperature, and tone. We cannot, 

 even in the present state of mathematical knowledge, 

 discuss the complex processes of nature as they are 

 presented to us ; for example, a mathematical law which 

 shall define all the changes of color, of electrical in- 

 tensity, etc., which occur when a body is heated, is 

 still beyond our powers. But it was possible, with the 

 knowledge then at hand, to abstract from matter all its 

 properties except that of a simple and uniform 

 space and force attribute, and to derive a theory of 

 mechanical action distinct and complete. And so the 



