THE SCIENCE OF HAPPINESS 



Any physical perversion of the brain is sure to be 

 recorded in a perversion of the mind. 



So much as this, stated in general terms, is doubtless 

 familiar knowledge nowadays to every intelligent 

 reader ; but I suppose there are many readers who have 

 but a very vague idea as to the anatomical conditions 

 that exist in the brain, and upon which the activity of 

 mind depends. It may not be amiss, then, to supple- 

 ment our studies of the action of mind with a brief 

 outline of the underlying brain conditions. Such a 

 study will perhaps make it easier to grasp the import 

 of a simple analysis of mental processes themselves. 



At the outset, then, it must be understood that the 

 brain is in effect an aggregation of nerve ganglia, and 

 that such an aggregation is found only among the 

 animals that are relatively high in the organic scale, 

 that is to say, among the vertebrates. With the very 

 lowest vertebrates, the collection of ganglia makes up a 

 spinal cord that is but slightly enlarged at its anterior 

 end to form a brain proper. But as we come up the or- 

 ganic scale, this anterior enlargement of the spinal cord 

 becomes more and more conspicuous (and the animal 

 correspondingly more intelligent), until finally in the 

 case of birds and mammals it is relatively enormous 

 in size. Man, at the head of the scale, has a brain that 

 is not only relatively the largest of all, but that is actually 

 larger than that of any other animals except the whale 

 and the elephant. 



The essential structures of the brain are minute cells, 

 and fibres that connect these cells with one another and 



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