982 Dynamic Theory. 



therefore, to be classed with the stomach and muscles as one of the 

 physical organs. It matters not what sort of a mental process goes .on, 

 we observe that it requires in every case the expenditure of blood. If 

 we take a run of a few rods we find the circulation of the blood greatly 

 accelerated, which means that the violent exertion has rapidly oxidized 

 the tissue involved, mostly muscular and nervous. But an acceleration 

 of the circulation may take place through purely mental excitement. 

 Horror, fright, anger, rage, and all the more violent emotions instantly 

 increase the circulation, when it is obvious that the expenditure of tissue 

 is that of the brain alone. The fact is the same with all the milder 

 emotions, love, admiration, hope, joy, &c. , to a less degree of course. 

 All the intellectual operations in like manner wear out brain tissue 

 which has to be replaced from the blood. The heating effect of mental 

 work and worry caused by an extra flow of blood is recognized in the 

 slang threat of " making it hot " for an antagonist, and the designation 

 of the witness' chair in legal slang as the "sweat box." It is also 

 seen in exciting mental games as of chess and cards; in the latter, how- 

 ever, more especially when accompanied with considerations of pecun- 

 iary value arousing emotions. In all sorts of gambling and speculating 

 the waste of brain tissue is great. The difference in the circulation of 

 the blood between sleep and a state of wakefulness, is of itself enough 

 to show the most passive sort of mentality to be a state of physical ac- 

 tion, the mere attention of wakefulness, however passive it may be, re- 

 quiring a greater expenditure of blood than is necessary in sleep. The 

 brain is a machine by means of which the forces in the environment 

 operate the muscles of the body. The movement imposed upon this 

 machine by these forces constitute the mind, and the mind is therefore 

 a necessary link in the chain of causation beginning in the sun and 

 elsewhere, and ending, so far as we are concerned, in the movement of 

 leg, arm, lip, tongue, eyelid, &c. The brain is divisible into two parts, 

 much the larger of which is used in forming mind, while the smaller 

 motor part is driven by the mind when formed. If a machine gets 

 damaged, broken, or worn out it fails to turn out a satisfactory product, 

 and so as we have seen, when the brain is damaged its products are im- 

 perfect or fail altogether. If the part of the brain operated % the 

 mind gets out of order, the force of the mind cannot drive it. This 

 happens in cases of disease in which the subject has full sensibility 

 without the power of executing a will, as in cases of defective cerebel- 

 lum, &c. (page 623. ) But if that part of the brain is diseased whose 

 function it is to form the mind, then the mind is erratic, and the sub- 

 ject is insane. A common opinion is that the mind (or soul) is an in- 

 telligent Person to whom the brain -is a rather unhandy and clumsy 

 tool, disappointing and exasperating at best; and that when the Mind 



