MENTAL ACTION IS EASILY EXCITED. 129 



govern also mental phenomena is a subject which would 

 amply repay extensive research. 



Volition is developed by education and habit ; an act 

 which at first requires conscious effort or * will ' in order 

 to perform it, sometimes becomes, by repetition and 

 custom, so powerful that we cannot restrain it ; the habit 

 of smoking is one of many possible examples. It is the 

 power of reason, rather than that of ' will,' ' which gives 

 to man his supreme dignity.' The enthusiastic use of 

 the will, unrestrained by reason (or ' I will have my own 

 way '), is a most dangerous power, and has led millions of 

 human beings to moral ruin and an untimely grave. 



We are often perfectly ignorant of the particular cir- 

 cumstances which really determine our choice and voli- 

 tion ; first, because most cerebral actions are unconscious 

 ones ; second, we often cannot survey our mental actions ; 

 and third, because of the extreme feebleness or minuteness, 

 in many cases, of the circumstances which cause us to 

 decide. The cerebrum is largely devoid of feeling, and 

 may be wounded without producing sensation ; multitudes 

 of actions occur within it of which we are unconscious, but 

 which, notwithstanding, more or less affect our course of 

 thought, and influence our choice. We are unconscious 

 of the continually occurring action most essential to 

 thought, viz. that of cerebral nutrition ; and also of that 

 operation of the brain and nerves by means of which 

 nervous discharges are transmitted. Conscious ideas often 

 arise, we know not how, frequently from a change in the 

 composition or quality of the blood, arising from the most 

 varied causes, the amount of free oxygen dissolved in it, 

 &c. ; and sometimes from additional blood flowing to the 

 brain. Ill-health often greatly diminishes volitional power. 

 The course of our thought is unconsciously diverted, and 

 our volitions thereby influenced, many times during a day. 



