MENTAL ASPECTS OF ORDINARY DISEASE. 563 



This change depends upon physical conditions, and a more pronounced 

 physical state not only involves the emotional centres, but implicates 

 the intellectual processes. Thus, a slight amount of bile in the blood, 

 or an excess of renal products, may depress a man with hopeless 

 despair or drive him into paroxysms of violent passion. The delirium 

 of fever is a familiar instance of the influence exercised by passing 

 bodily conditions upon the brain and its product thought. 



When the nutrition of the brain is good, we experience an agree- 

 able sense of well-being, which shows itself distinctly in after-dinner 

 geniality. When the nutrition is imperfect, or the arterial blood is of 

 abnormal composition, the consequences are a mixture of irritability 

 and bad temper, blended with depression. We are all familiar with 

 the crossness of the hungry man ; when fasting, crossness is inter- 

 changeable with hunger is often its substitute, and forms a contrast 

 with the amiability of repletion. Especially is this irritability seen 

 in those whose digestive powers are weak. A similar irritability 

 is the ordinary mental attitude of convalescence from acute disease, 

 and either precedes or runs into and coexists with the keen appetite 

 usually found at that time. They are linked together by something 

 more positive than coincidence. 



The dependence of modifications of the functional activity cf the 

 cerebral cells upon other corporeal conditions than changes in the 

 blood is now well recognized. There are communicating fibres by 

 which the brain receives impressions of varying character from dif- 

 ferent organs. An impression coming in from some far-away point 

 stimulates or inhibits the action of the cerebral cells. So strong may 

 be the impression that actual insanity may result, as in the case, re- 

 lated by Schroeder van der Kolk, of a lady who became insane when- 

 ever her womb became displaced, and sane again as soon as it was 

 returned to its place. 



The effect of several morbid states is to stimulate the brain into 

 greater activity. A non-medical but most acute observer and able 

 writer ' says : 



" It seems even that bodily pain and disease are not only compatible with, 

 but may directly contribute to, the loftiest efforts of the intellect. They some- 

 times positively enhance its powers. The effect of some disorders and of certain 

 sorts of pain upon the nerves is to produce a cerebral excitation ; and the stimu- 

 lus thus communicated to the material organ of thought renders it for the time 

 capable of unusual effort. Men under the stirring influence of severe pain are 

 capable of a degree of imaginative and ratiocinative brilliancy which astonishes 

 themselves and all who have known them only in ordinary moods of comfort. 

 Torpid faculties become vigorous and sparkling. Forgotten knowledge is re- 

 covered. Marvelous gleams of insight are vouchsafed them. The wonderful elo- 

 quence of Robert Hall was doubtless greatly owing to the stimulating influence of a 

 terrible spinal malady. Dr. Conolly mentions a gentleman whose mental facul- 

 ties never reached their full power except under the irritation of a blister. Ab- 



1 " The Enigmas of Life," by W. R. Greg. 



