114 LETTERS TO BROTHER JOHN. 



and sinews are so firmly compressed on all sides by 

 the unyielding structure of these parts, that they 

 are almost wholly insensible. You may cut them, 

 lacerate them, without giving pain. The muscles 

 (that is, the red flesh) cannot be wounded without 

 considerable pain, because their structure is not so 

 firm as that of the bones, sinews, &c. : but it is 

 much more compact and firm than the structure of 

 the skin, and therefore a wound inflicted on a 

 muscle will not produce any thing like the acuteness 

 of pain which is felt on wounding the skin. In 

 the nerves of the eye and ear it was necessary that 

 a SENSIBILITY of the very highest degree should 

 exist, in order to enable these organs to feel the 

 very slight and subtile impressions of light and 

 sound. Accordingly, we find that from these nerves 

 all surrounding pressure is removed entirely; these 

 nerves being, as it were, expanded into a sort of 

 quivering jelly at that part where they are destined 

 to receive their natural impressions. 



Now, a very large portion of the body is, as you 

 know, made up of a conglomeration of blood- 

 vessels. The whole body, then, taken as a whole, 

 will be the more compact and firm accordingly as 

 these vessels are fully distended with blood ; pre- 

 cisely as sponge becomes a more compact body 



