352 CREATIVE EVOLUTION CHAP. 



What distinguishes modern science is not that it is 



O 



experimental, but that it experiments and, more 

 generally, works only with a view to measure. 



For that reason it is right, again, to say that ancient 



science applied to concepts^ while modern science seeks 



^Jaws, constant relations between variable magnitudes. 



I The concept of circularity was sufficient to Aristotle 



/ to define the movement of the heavenly bodies. But, 



&quot;~even with the more accurate concept of elliptical 



form, Kepler did not think he had accounted for 



the movement of planets. He had to get a law, that 



is to say, a constant relation between the quantitative 



variations of two or several elements of the planetary 



movement. 



Yet these are only consequences, differences that 

 follow- from the fundamental difference. It did happen 

 to the ancients accidentally to experiment with a view 

 to measuring, as also to discover a law expressing a 

 constant relation between magnitudes. The principle 

 of Archimedes is a true experimental law. It takes 

 into account three variable magnitudes : the volume 

 of a body, the density of the liquid in which the body 

 is immersed, the vertical pressure that is being exerted. 

 And it states indeed that one of these three terms is a 

 function of the other two. 



The essential, original difference must therefore be 



sought elsewhere. It is the same that we noticed first. 



^ 



The science of the ancients is static. Either it 

 considers in block the change that it studies, or, if 

 it divides the change into periods, it makes of each of 

 these periods a block in its turn : which amounts to 

 saying that it takes no account of time. But modern 

 science has been built up around the discoveries of 

 Galileo and of Kepler, which immediately furnished it 



