848 The Outline of Science 



however, if there are degrees of reality, is our inner life of con- 

 sciousness, our stream of thoughts and feelings, desires and pur- 

 poses. It is our supreme reality, for it includes all others, and no 

 theoretical view can stand that is subversive of this reality. (3) 

 But the third certainty is that organism and personality, body 

 and mind, nervous metabolism and consciousness, are in the ex- 

 perience of everyday life interdependent. It is a relation, there 

 is nothing to which we can compare it ; if it is a unity, it is equally 

 unique. We are mind-bodies or body-minds; sometimes we feel 

 more of the one, sometimes more of the other." 1 That, however, 

 as we have seen, will form the subject of a later chapter. 



We may note here that it is a popular fallacy to suppose 

 that all the contents of the skull are concerned with thought and 

 feeling, or that a large head means a large capacity. The bulk 

 of the matter in the cranium has nothing to do with thought. It 

 is only a very thin rind or cortex of nervous matter, about a ninth 

 of an inch thick on the average, covering the fore-part of the brain 

 (from the top of the head to the base of the forehead) which is 

 the organ of consciousness. But this precious cortex is an intri- 

 cate structure made up of 9,200 million nerve-cells, and it is in 

 man folded and creased so as to pack as much surface as possible 

 within the limits of the human skull. Round this central area are 

 the nerve-centres for controlling the muscles of the head, face, 

 eyes, tongue, and the like ; and the centres for receiving the reports 

 of the eyes, nose, and ears are also in the brain. In a man who 

 weighs 150 Ibs., the nerve-cells of the brain-cortex would weigh 

 about -sthfTs part of the total, but this small part controls the 

 whole. 



At the back of the head is the cerebellum, or "small brain" : 

 the chief centre for co-ordinating the movements of the muscles 

 so as to produce harmonious action. If it has been injured in a 

 bird or a dog, the animal can no longer stand up or maintain a 

 balance of movement. All day long the cerebellum must be re- 



1 Professor J. Arthur Thomson, The Control of Life. 



