CH. III.] ACTIONS OF INSTINCTS. 143 



tf° 



Even excessively pleasurable feelings, which border upon the 

 contra-natural (199), cease to be an object of gratification, 

 d are abhorred (191, 80, 81). 



iv. The sentient actions of the agreeable sensational instincts 

 all agree in this, that if not excessive_, they are conformable 

 with the welfare of the body, but if excessive, they are like 

 the sentient actions of the unpleasant instincts, and are opposed 

 to it (259). But inasmuch as all have the best interests of the 

 animal in view (263), the latter are only serviceable so far as they 

 act like medicine, and compel the animal by abnormal actions to 

 pass from a condition injurious to it, and therefore opposed to 

 their object (as, for example, a state of indifference, of pleasure, or 

 of misery), into the opposite and more salutary condition (196). 



V. The sensational stimuli, whether pleasurable or painful, 

 which have to excite the curative instincts of the animal 

 (270, 271), operate sometimes in this way, by maintaining the 

 health of the animal, of sometimes contrarily thereto, according 

 as they are either pleasurable or painful (252). Thus fasting, 

 which is the sensational stimulus of hunger, makes us ill, and 

 compels us to think of feeding ourselves. 



vi. Since the gratification of all instincts is an agreeable ex- 

 ternal sensation (276, iii), their sentient actions in the body are 

 generally in accordance with its nature and welfare (196), pro- 

 vided they are not excessive (199). Thus the gratification of the 

 appetite for food, for sexual congress, &c., conduces to health, pro- 

 vided the appetites are not excessive ; in the latter case, however, 

 they cease to be agreeable, and are abhorred (excite disgust). 



277. The combination of so many corporeal influences in 

 each instinct (which act partly from without through the 

 nerves, and are partly sentient actions of various kinds), renders 

 the explanation of the resulting corporeal phenomena pecu- 

 liarly difficult ; a knowledge of the peculiar sources of each of 

 these influences is, however, of considerable assistance. These 

 influences are : 



i. The actions of the natural inducements of the instinct. 

 These inducements are external impressions on the nerves, 

 which they prepare before-hand, in a peculiar way, to receive the 

 sensational stimuli proper to the instinct (264). 



ii. The sentient actions of the sensational stimuli on the 

 vital movements (271). 



