RELATIONS OF EXPERIMENTAL PSYCHOLOGY 657 



The logical systematization of any order of phenomena is thus 

 supplemented and controlled by a consideration of the various 

 classes of associated phenomena upon which in our thought we 

 find ourselves most frequently and seriously depending. If the 

 physiologist constantly refers to the work of the chemist, and finds 

 the theorems of that science indispensable to the successful prosecu- 

 tion of his own investigations, the methods and subject-matter 

 of the two disciplines must have common elements in theory as 

 well as practice, and their relations cannot be overlooked in any 

 scheme of classification which includes both sciences. For those, 

 therefore, who have more than a formal interest in the matter 

 there must always be profit in a study of the various special sci- 

 ences with which in the actual progress of knowledge any given 

 type of investigation is most frequently brought into contact. I 

 shall therefore put aside as far as possible questions of purely 

 logical import, and confine my attention to associations of the 

 latter type. 



Two orders of relationship are here presented. The first of these 

 is the question of historical origin, the second that of functional 

 interaction. The consideration of the series of historical develop- 

 ments out of which a given science has arisen, however, leads one 

 to an importantly different set of associates from those with which 

 its activities at the time being are most frequently and significantly 

 allied. Psychology did not arise either by division or exclusion 

 from physiology, yet the methods and results of that science are 

 more frequently discussed and made use of by the psychologist 

 than those of philosophy, from which his science has had its his- 

 torical origin. 



It is to relations of the second type, it may be assumed, that 

 expectation chiefly turns in discussions concerning the place of 

 any given science. These fall into two general classes according 

 as they express relations of dependence or support. By their side 

 both matters of logical classification and questions of origin are 

 of secondary importance. One wishes to know of a science, as of 

 a man, what it is doing in the world rather than its descent and 

 family connections. A knowledge of the sciences to which it is 

 indebted, for points of view or for results, and of those to 

 which in its turn it contributes, will go farther toward affording 

 an understanding of its place in the general system of knowledge 

 than any amount of formal and antiquarian information regard- 

 ing it. 



Before taking up the discussion of these positive relations, how- 

 ever, it may be advisable to discriminate psychology from two 

 adjacent branches of study with which its function has not infre- 

 quently been confounded. On the one hand, psychology has been 



