212 



PHILOSOPHICAL THOUGHT. 



18. 



Errors of 

 this pro- 

 cedure. 



which were committed by the logic of these thinkers 

 were manifold, but two of them may be singled out not 

 only as fatal to ultimate success but also as highly 

 dangerous, inasmuch as their seductive nature prevented 

 them from being readily detected, and because they were 

 extremely difficult to destroy when once the popular 

 understanding had given them an entry. 



To begin with, the terms matter and force referred to 

 notions which might appear clear to the popular mind, 

 inasmuch as they were in daily use in common language, 

 and as such seemed to convey a definite meaning. It 

 was therefore an irony of fate that just about the 

 time when these terms were placed at the head of a new 

 philosophy and made the foundations, as it were, of a new 

 creed, these same terms were being discarded from strict 

 scientific treatises, and others being introduced which 

 were capable of rigorous definition. The term matter 

 was to be replaced in dynamical treatises by the word 

 mass or inertia, and the word force had to give way 

 to the less equivocal term, energy. Both mass and 

 energy could be mathematically defined in terms of the 



perience and observation, whereas 

 the introduction of the so-called 

 principles or fundamental notions 

 of physics and chemistry led rather 

 to an abstract and contracted view 

 of mental phenomena, to hasty 

 generalisations, and, in the end, to 

 purely verbal distinctions. In this 

 country, in spite of the fact that the 

 principles of exact science, the laws 

 of motion, were first laid down and 

 clearly defined in the ' Principia ' of 

 Newton, little was done to examine 

 clearly and to define the range of 

 applicability of these iprinciples. 

 Natural science was limited almost 

 exclusively to observation and ex- 



periment. It was only through the 

 French mathematicians, in the 

 course of the eighteenth century, 

 that the Newtonian principles were 

 more clearly brought out, and only 

 through Lavoisier that the con- 

 servation of mass, or rather the 

 constancy of the weight of bodies, 

 was made the foundation of modern 

 chemistry. In Germany, on the 

 other hand, the principles of dy- 

 namical and physical research were 

 discussed in a philosophical spirit 

 by Leibniz, in whom the tendency 

 of the German mind to deal with 

 fundamental questions was for the 

 first time clearly exhibited. 



