Psychophysical Parallelism in Evolution 13 



be explained in a little more detail, after which certain 

 applications of the two preceding principles — continuity 

 and uniformity — may also be indicated. 



§ 4. Psychophysical Parallelism in Evolution 



I have said that the principle of parallelism is universal, 

 that is, that it is applicable to all instances in which the 

 facts on either side are of the order indicated by the term 

 * psychophysical.' The great spheres in which such a truth 

 would have bearings are the two covered by individual life 

 history, from life to death — ontogeny, the sphere of 

 development — and the race history of a species, or of all 

 life upon the earth considered as showing a series of forms 

 connected by links of progressive descent — phylogeny, or 

 evolution. These two forms of parallelism we may call 

 respectively 'individual' and 'racial.' Earlier discussions 

 of parallelism have had reference largely to the former 

 sphere, and the question has come up for the most part in 

 connection with theoretical discussions of the relation of 

 mind and body. Furthermore, the concomitance of 

 development of mind and body in the individual has had 

 recognition, and its illustrative value for the topic of evolu- 

 tion has been written about — though not at all adequately. 



The corresponding racial application of parallelism in 

 the sphere of evolution has not, to the present writer's 

 knowledge, been explicitly made ; that is, as going neces- 

 sarily with an individual parallellism, as part of an in- 

 tergenetic conception. And yet the two cases must 

 necessarily go together, and no final formulation is 

 possible of the relation of conscious changes to bodily 

 changes which does not have direct application in both 

 these spheres, and indeed the same application in both 



