CONCLUSION 225 



nections of phenomena. The task was immense, and 

 in order to accomplish it successfully it was necessary 

 to surmount difficulties which appeared insoluble. 



These difficulties having been overcome, it might 

 have been believed that the way was definitely open 

 and that it was only necessary to advance along it 

 without fear of meeting with insurmountable obstacles. 

 As a matter of fact, until the beginning of the twentieth 

 century, the conception of scientific law, formed by 

 the scientists of the Renaissance, was not seriously 

 shaken. According to this conception, there exist, at 

 the base of all science, rational and experimental laws 

 which having once been discovered are eternally true 

 and incapable of modification. Hence, it is only 

 through the more and more extended application of 

 these laws that science in all its branches will make 

 progress. 



We know how the theory of relativity enunciated 

 by Einstein and upheld by Langevin has shaken this 

 conception and put in check certain postulates of the 

 Newtonian kinematics. It is a curious fact that the 

 partial abandonment of the conceptions formulated 

 in the sixteenth and seventeenth centuries marks at 

 the same time a return to many of the opinions held 

 by Greek science in antiquity ; this return is all the 

 more significant because it was unpremeditated. It 

 is beyond question that analogies, both as regards 

 hypotheses and methods, can be found between the 

 physics of relativity and the cosmology of the ancient 

 Greeks. 



The first philosophers of Ionia, for instance, did not 

 distinguish between an empty space which would be 

 self -existent, and a fluid substance (air, water or fire) 

 which would accidentally fill it. In their eyes there 

 was no separation between the physical properties of 

 space and space itself. In the physics of relativity the 

 same thing occurs in a form, needless to say, infinitely 



