LETTERS TO BROTHER JOHN. 117 



TRACTILITY, but also of the circulating power : and 

 since all the motions of the body are performed by 

 virtue of CONTRACTILITY, and the whole process of 

 nutrition by the virtue of the circulation, this is 

 the same as saying that the degree of SENSIBILITY 

 is always in an inverse ratio of the degree of 

 health and strength ; which is the fact. 



A very familiar instance of the increase of SEN- 

 SIBILITY, produced by lessening the quantity of the 

 blood, is to be found in the fact, that a dose of 

 cathartic medicine wholly incompetent to affect the 

 bowels under ordinary circumstances, will be found 

 quite sufficient to do so if administered after blood- 

 letting. 



I am at this time attending a huge, strong, dread- 

 nought-looking custom-house officer, for a slight 

 attack of paralysis which he sustained some weeks 

 since. Since the attack, I have bled him nine times, 

 taking away thirty ounces of blood each time: he was 

 also once cupped by Mr. Gomley of Osborn Street. 

 You may easily imagine that a man who can bear 

 this, and yet walk about the street without support, 

 must, at least, be no chicken. Yet so much has 

 his sensibility (I speak now of moral SENSIBILITY, 

 which, after all, is but the physical SENSIBILITY of 

 those parts of the nervous system which are suscep- 



