44 



beyond the compound co-ordination just described, resembles 

 a piano that is silent until touched by the hands of the per- 

 former. Its nervous system is played upon by external 

 objects, the clustered properties of which draw out answering 

 chords of feelings, followed by faintly reverberating chords of 

 further feelings; but it is otherwise passive it cannot evolve 

 a consciousness that is independent of the immediate environ- 

 ment. How does such independent consciousness become 

 possible? When do ideas, rightly so-called, arise? They arise 

 when compound co-ordination passes into doubly-compound 

 co-ordination. They grow distinct in proportion as the 

 correspondence exists in space and time. They acquire a 

 separateness from direct impressions as fast as there increase 

 those series of clustered sensations which unite the visual 

 sensations received from objects out of reach with the tactual 

 sensations afterwards yielded by such objects. * * * They are 

 the necessary concomitants of that process by which, through 

 intercalated psychical states, there is established a mediate 

 relation between psychical states that cannot be brought into 

 immediate relation. And they have for their seats those in- 

 tercalated plexuses which co-ordinate the co-ordinating 

 plexuses previously existing. That is to say, ideas form a 

 larger and larger portion of consciousness as fast as there 

 develop these two great pedunculated nerve-centres which 

 distinguish the superior animals; ideas become more multi- 

 tudinous and more separable from direct sense impressions 

 as these centres increase in size and structure; and eventually 

 when these centres are highly evolved, ideas admit of com- 

 bination into trains of thought that are quite independent of 

 present external perceptions." 



"By carrying a step further the illustration used in the 

 last section, we may now get a better notion of the parts which 

 the cerebrum and cerebellum play in mental processes. For 

 just as, by the actions of appropriate mechanisms joined to 

 them, musical instruments of certain kinds are made to yield 

 musical combinations without the hands of the performer; so, 

 through the workings of these great appended nerve-centres, 

 there are called out from the centres below them trains of 

 consciousness independent of, or additional to, those aroused 

 by impressions on the senses. * * * We see, in short, that the 

 medulla oblongata (with its subordinate structures) while 

 played upon through the senses by external objects, is simul- 

 taneously played upon by the cerebrum and cerebellum; so 

 producing the thought consciousness that accompanies sense 

 consciousness." Respecting emotions, "it has only to be 

 added that they, like ideas, result from the co-ordinating 



