OF NATURE. 565 



what I termed, in the first section of this history, the 

 astronomical and the atomic views of nature. The kinetic 

 view was still only very imperfectly developed. The 

 conception and term energy did not exist. The peculiar 

 properties which attach respectively to vibratory, rota- 

 tional, and translatory motion, and the definite part 

 which each played in the description of physical 

 phenomena, were not clearly understood. Further, the 

 second law of thermodynamics, the dissipation of energy, 

 was unknown to all but a very small number of the 

 foremost thinkers. And lastly, the theory of descent 

 and of the transmutation of species had not yet been 

 formulated in a manner which made it useful for an 

 exact comprehension of biological phenomena. We can 

 not therefore be surprised that Biichner's work was 

 acceptable neither to the representatives of exact science 

 nor to those of philosophy. It was the first bold at- 

 tempt to develop a detailed creed by means of concep- 

 tions familiar to all naturalists as well as to common- 

 sense, but clearly defined only in the minds of very few 

 amongst the foremost thinkers. What characterised its 

 attitude was a dogmatic assertion of theories which 

 could never be proved, and the use of conceptions 

 which were not clearly defined, and which were in fact 

 assumed to be undefinable. Nevertheless, with terms is. 



. Inadequacy, 



such as matter and force, the popular mind is accus- yet popu- ' 



larity, of 



tomed to connect a definite meaning which is founded a ' n ^ atter 

 upon special sensations such as extension, pressure, or " 

 weight. Now there is no doubt that the popular mind 

 connects a definite meaning also with such terms as idea 

 and spirit. This is evident from the fact that these 



