THE ATOMIC VIEW OF NATURE. 401 



the chemist was enormous, offering a large, almost limit- 

 less, field of research and speculation. Let us see under 

 what leading ideas this knowledge has been arranged. 



In the gradual development and clearer definition of 

 these conceptions a general rule of thought seems to 

 have unconsciously guided philosophers probably more 

 than in any other department of knowledge. It is the 

 rule of simplicity. 1 How the human mind should have H. 



" Simplex 



arrived at the old formula of " simplex sigillum veri " is sigiiium 



veri." 



difficult to understand on any other ground than that of 

 convenience and expediency. The prevailing impression, 

 indeed, which the world of phenomena makes on the mind 

 of an unbiassed observer must be the very reverse of sim- 

 plicity or unity of law and purpose. That, nevertheless, 

 the knowledge of some simple relations in time, number, 

 and space would enable the human intellect to acquire a 

 considerable insight into the course of events and the 

 order of Nature's processes must have come to philosophers 



1 The progress'of chemical theory ! notion of a molecule, an assemblage 



is the history of the attempt to [ of atoms ; the conception of elemen- 



find simple relations of number and i tary bodies had to be amplified by 



form, representing the countless that of compound elements or 



combinations of elementary sub- 

 stances ; and of the growing con- 

 viction that nearly every simpli- 

 fication must, in course of time, 

 be abandoned. No formula remains 



radicles ; the idea that the atomic 

 weights were multiples of a lowest 

 number had to be abandoned ; the 

 binary theory of the combination 

 of bodies was replaced by the theory 



unchallenged except the doctrine of of radicles, of nuclei, of types ; the 



fixed and fixed multiple proportions, j simple nature of the elementary 



and that only if we confine our- , particles had to give way to a 



selves to solid compounds ; but the complicated atomicity, from which 



proportions themselves are not ac- there had to be again distinguished 



curately known, though no pheno- the valency or capacity of satura- 



menon exists which disproves the tion of the elementary constitu- 



assumption that they are invariable. | ents. It is a progress from simpler 



The original conception of the atom to more and more complex methods 



as a round hard body had to be of representation, 

 abandoned for the more complicated 



VOL. I. 2 C 



