THE NATURE OF STIMULATION 29 



The problem of all scientific research consists wholly in the 

 ascertaining of the conditional interdependency. 



A state or process is solely determined by the sum total of its 

 conditions. A state or process is identical zvith all of its condi- 

 tions in totality. From this it follows that equal states or pro- 

 cesses are always the expression of equal conditions and where- 

 ever unequal conditions exist, unequal states or processes will 

 result; and further, a state or process is completely investigated 

 when the entire number of its conditions is ascertained. 



This fundamental statement of conditionism should be en- 

 graved over the portals to the entrance of every scientific inves- 

 tigation. 



That there is not the least difficulty in presenting scientific 

 observations strictly according to these principles of conditionism, 

 and that one can perfectly well do without the causal conception 

 in a scientific description, I have shown by a concrete example, 

 namely, in the fifth edition of my "General Physiology." In the 

 whole volume the conception of cause is only mentioned in one 

 place, where its theoretical value is criticised, elsewhere not at 

 all, and yet I do not think that any one will miss this conception, 

 and indeed, if their attention is not especially called to the fact, 

 even notice the omission. 



These principles of an exact conditional investigation must also 

 guide us in the analysis of the processes of stimulation. The 

 process of stimulation is especially apt to tempt one to employ 

 the old conception of cause, for it belongs to that group of pro- 

 cesses which originate from an already existing system by the 

 addition of a new factor. An electric stimulus acts on the muscle. 

 The muscle contracts. The stimulus is considered the cause of 

 the contraction. But what would I explain if I were to prove 

 that the stimulation is the cause of the contraction? 



The history of physiology shows us that this subject has ad- 

 vanced long since far beyond the stage of being satisfied with 

 such an explanation. Today the process would only then be 

 fully investigated if we knew the entire number of its conditions 

 and had traced the dependency of the individual partial con- 

 stituents of the whole complex process upon one another. For 



