THE HISTORY OF PSYCHOLOGY 611 



so far attributal to each other, that either can be predicted on 

 occasion as either cause or effect with reference to the other. This 

 was notably true in the entire church development; and the view 

 is still dominant in theology. This cause and effect bond is the 

 last one that remained to be loosed. 1 



In Descartes, for the first time in the history of thought, cer- 

 tainly of Occidental thought, is the psycho-physical problem spe- 

 cifically set in the form of the conception of a natural relation 

 between mind and body, considered as two separate substantial 

 principles. The problem becomes: what is the relation? It as- 

 sumes not only the dualism of the two terms, but their actual 

 separation. Descartes not only reaches such a dualism, but he 

 sets up the firil relational problem of mind and body. And further, 

 he identifies the spiritual principle with "inner experience" or 

 "thought." He is in advance of the church philosophy in this 

 important respect, that while, to the latter, it was a problem of sepa- 

 rating mind and body, to Descartes it was a question of bringing 

 them together again. Descartes said that interaction was impossible; 

 and the theory of preestablished harmony was the alternative. 



Why, then, it may be asked, did not a purely naturalistic psych- 

 ology begin with Descartes? For much the same reason, I sur- 

 mise, that it did not begin with Aristotle: because Descartes did 

 not conceive the inner principle, the soul or thought, in terms of 

 continuous and lawful change. Just in this was it contrasted with 

 body. Extension is the sphere of geometry and physics; thought 

 is the source of spiritual manifestations; and these two domains 

 of fact, though parallel, are essentially heterogeneous. That this 

 is true of Descartes is proved historically; just as the correspond- 

 ing fact comes out in the comparison of Aristotle with Socrates. 

 In each case a monistic idealism followed, not a scientific natural- 

 ism. Socrates was followed by Plato, Aristotle by a new mysticism, 

 while Descartes led right on to Spinoza. In each case, we find 

 an attempt to transcend the specific form of dualism of its own 

 period. 2 



a principle. When the dualism arose, however, such views availed themselves 

 of so much support, just as modern theology supplies a doctrine of immortality 

 in support of the early anthropological belief in a world beyond. Put in psycho- 

 logical terms, we may say that such early religious and anthropological views 

 were object of practical and, in some cases, esthetic interest, but not of the 

 sort of theoretical interest which leads to philosophical inquiry. 



1 I have pointed out elsewhere (Psychological Review, May, 1903) that the case 

 of mind and body is the last instance of that sort of commingling of substances 

 and forces. It is present in all the forces involved in " interaction " theories. 



1 It is an interesting point that in each such case, the supposed reconcilia- 

 tion is not logical, but, in a broad sense, esthetic: the motive in Plato is poetic, 

 in the Post- Aristotelians it is mystic, in Spinoza it is religious,- 1 - a matter it would 

 be well to expound in its own place. It has its parallel, moreover, in the indi- 

 vidual's mode of treating his dualisms, i. e., by the construction of objects 

 which are valid from esthetic points of view. This is, I think, the normal genetic 

 outcome. 



