232 ON THOUGHT IN MEDICINE. 



the principle may appear to be, that natural science has 

 to seek for the laws of facts, this principle is neverthe- 

 less often forgotten. In recognising the law found, as a 

 force which rules the processes in nature, we conceive it 

 objectively as a, force, and such a reference of individual 

 cases to a force which under given conditions produces 

 a definite result, that we designate as a causal explana- 

 tion of phenomena. We cannot always refer to the 

 forces of atoms ; we speak of a refractive force, of electro- 

 motive and of electrodynamic force. But do not forget 

 the given conditions and the given result. If these 

 cannot be given, the explanation attempted is merely 

 a modest confession of ignorance, and then it is decidedly 

 better to confess this openly. 



If any process in vegetation is referred to forces in 

 the cells, without a closer definition of the conditions 

 among which, and of the direction in which, they work, 

 this can at most assert that the more remote parts of 

 the organism are without influence ; but it would be 

 difficult to confirm this with certainty in more than a 

 few cases. In like manner, the originally definite sense 

 which Johannes Miiller gave to the idea of reflex action, 

 is gradually evaporated into this, that when an impres- 

 sion has been made on any part of the nervous system, 

 and an action occurs in any other part, this is supposed 

 to have been explained by saying that it is a reflex 

 action. Much may be imposed upon the irresolvable 



