188 CAUSATION OF MENTAL 



paper that startles and alarms one horse and sends it off in 

 a panic-flight may produce a stampede in a whole troop. 

 Here imitation or sympathy comes largely into play in the 

 epidemic diffusion of the terror, and of the impulse to flight 

 from an imaginary, utterly undefined danger. 



Much fear, especially in panic, appears to be absolutely 

 causeless or groundless. Thus Pierquin refers to causeless 

 dread and panic in the sheep. Likings or fancies, as well as 

 antipathies or hatred, fright or fear, delusive panic, and all 

 the forms of insanity may, and do, appear without any obvious 

 external, assignable cause. That is to say, we cannot, or 

 do not, determine the probable cause or causes. 



Causelessness, however, or triviality of cause may be only 

 apparent. It may be due to want of proper inquiry or ob- 

 servation, or to man's ignorance of the etiology of insanity 

 in the lower animals. 



As in man, the same causes do not always operate in the 

 same way in 



a. Different genera and species ; in 



6. Different individuals of the same species ; or in 



c. The same individual at different times or under dif- 

 ferent circumstances. 



d. They may be hurtful or operative at one time, and 

 innocuous at another. 



e. All causes are liable to be modified by individual 

 peculiarities of temperament, disposition, or habit ; by 

 idiosyncrasies, physiological or pathological. And hence it 

 is that the same simple cause so frequently produces dif- 

 ferent results in different individuals. 



In other words, the same causes may produce the most 

 diverse results. Thus the same poisonous agent or drug 

 begets different classes of mental symptoms in different 

 individuals, and still more in different genera and species. 

 The same terrifying object may produce either 



a. Stimulation of energy, increased action of the mental 

 faculties, leading to regulated flight ; or 



b. Confusion of ideas a state of mental bewilderment, 

 ending in self- destructive follies of precipitancy, thought- 

 lessness, or heedlessness ; or 



