PHYSIOLOGY. 123 



body at present is more ready to imagine that it is the effect of 

 the pleasure that induces a relaxation of the system, and further 

 takes off an irritation that had been considerable before. All 

 sorts of gratifications thus induce some degree of relaxation, 

 languor, and somnolency ; but what I mean especially to men- 

 tion here, is a full stomach. A brute animal no sooner fills his 

 belly than he goes to sleep : man has the same disposition. It 

 has been accounted for, agreeably to the theory I have men- 

 tioned, by its compressing the descending aorta, and thereby 

 sending more blood to the head, and occasioning a compression 

 of the head ; but Dr. Haller positively refuses that in man the 

 fullness of the stomach operates in this way ; it evidently will 

 not apply to those animals which are prone, and in which it 

 may stretch the integuments, but cannot act upwards to com- 

 press the aorta ; and it will hereafter appear from some con- 

 siderations, which we shall use against compressions having any 

 effect, that it must be somewhat in the sensation, somewhat in 

 the satiety, somewhat in removing the irritation which had in 

 some way acted upon the system. 



" I go on to say, in the next place, that ' sedative sensations 

 and impressions'" are the cause of sleep. The sedative sensa- 

 tions, as fear and grief, are by our pathologists considered 

 among the pathemata reprimentia, which have a direct ten- 

 dency to diminish the motions of the system in general ; that they 

 are such I need not prove, but that they are causes of sleep is not 

 so evident. But I know that they naturally induce sleep ; it is a 

 practice with nurses to frighten their children a little, and common- 

 ly with the effect of laying them more quickly asleep; and I know 

 more than one person who, when affected by an irrecoverable loss 

 as a mother for the loss of a child, where her grief can suggest 

 no redress readily fall asleep. I know several instances of 

 such persons being disposed to sleep, and to sleep a great deal. 

 With regard to our passions, I would observe, that there is such 

 a variety that is is not easy to observe an uniformity, and this 

 has been marked as a proof of their indifference ; but I find that 

 where they produced sleep, the mind was thrown into such a melan- 

 choly state, as naturally produced this disposition to sleep ; and this 

 view of the matter agrees with our general plan; it suspends all 

 the operations of the mind, it is an attention to one single ob- 



