466 Edward Livingston Youmans, 



the outlook is confident, there is joy in action, and 

 courage in enterprise ; but with a low or disturbed cir- 

 culation, thin, morbid blood, and bodily exhaustion, there 

 is depression of spirits, gloom, inaction, paralysis of will, 

 and weariness of life. That variability of mental state 

 which is so striking and general an experience with the 

 literary and artistic classes, the periods when work is im- 

 possible, the moods of sluggish and unsatisfactory effort, 

 the seasons of steady and successful accomplishment, and 

 the moments of rare exaltation, capricious as they may 

 seem, are but the exponents of varying constitutional con- 

 ditions. 



But the part played by the organism becomes still more 

 in^apparent when we consider the mode of action of the 

 stated TiH^ system in producing mental effects. It has been 

 hence the simoi^^'^^ system is composed of fibres and cells ; 

 where a cell and fibre conceivable case of nervous activity is 

 ment and a discharge the'^tll^^ active, producing an excite- 

 being nothing more t'han a complex^^'^ ^''^'^'' ""^ ^^^ '''^^'' 

 and discharges. In sleep, for example^^'^'^^'^ °^ excitements 

 the face, producing an impression, or ch'a?^ ^ ^^ ^^^[^ ^^^^ 

 a discharge along the nerves to the ^re>'^^' ^^'""^ ^^"^'^^ 

 spinal cord. Here force is again liberated ^^ "^^''^l ^^ '}^ 

 charged along another set of nerves upon the ^''^'' '' .'^'" 

 muscles, which, being contracted, bring the har^?m'' 

 place where the fly settled. This is the course of'^^^' ' 



a simple reflex action. But when the brain is ca'P'' TT' '"^ 

 conscious exercise in the higher processes of inte^'f f,"^ 'T 

 just the same thing occurs. A person may be engal^'^^''^'' 

 tranquil thmking, when one idea leads on to another Y. 

 natural tram of association-that is, where the excitem^'^lf " 

 of one state of consciousness is discharged into anoth ""^^'l' 

 formmga succession of cerebral changes. In this qui?^ 

 course of thought, a ludicrous idea or a witty combination"^ 



