260 P8TCH0L0GT. 



late it into the real form by keeping note of the way they 

 are placed or held. In no other class of sensations does 

 this incessant correction occur. What wonder, then, that 

 the notion ' so placed ' should invincibly exert its habitual 

 corrective effect, even when the object with which it com- 

 bines is only an after-image, and make us perceive the latter 

 under a changed but more ' real ' form ? The ' real ' form 

 is also a sensation conjured up by memory ; but it is one so 

 •probable, so habitually conjured up when we have just this 

 combination of optical experiences, that it partakes of the 

 invincible freshness of reality, and seems to break through 

 that law which elsewhere condemns rejjroductive processes 

 to being so much fainter than sensations. 



Once more, tlwse cases form an extreme. SomeivJiere, in 

 the list of our imaginations of absent feelings, there must be found 

 the vividest of all. These optical reproductions of real form are 

 the vividest of all. It is foolish to reason from cases lower 

 in the scale, to prove that the scale can contain no such ex- 

 treme cases as these ; and particularly foolish since we can 

 definitely see why these imaginations ought to be more 

 vivid than any others, whenever they recall the forms of 

 habitual and probable things. These latter, by incessantly 

 repeated presence and reproduction, will plough deep 

 grooves in the nervous system. There will be developed, 

 to correspond to them, paths of least resistance, of unstable 

 equilibrium, liable to become active in their totality when 

 any point is touched off. Even when the objective stimulus 

 is imperfect, we shall still see the full convexity of a human 

 face, the correct inclination of an angle or sweep of a curve, 

 or the distance of two lines. Our mind will be like a poly- 

 hedron, whose facets are the attitudes of perception in which 

 it can most easily rest. These are worn upon it by habitual 

 objects, and from one of these it can pass only by tumbling 

 over into another.* 



Hering has well accounted for the sensationally vivid 

 character of these habitually reproduced forms. He says, 



* In Chapter XVIII, p. 74. I gave a reason why imnginations ought not 

 to be as vivid as sensations. It should be borne in mind that that reason 

 does not apply to these complemental imaginings of the real shape of 

 things actually before our eyes. 



