LETTERS TO BROTHER JOHN. 161 



body and mind themselves, are under the dominion 

 of the circulation of the blood, from which both 

 mind and body must inevitably derive each its tone 

 and character. So that "the body and the mind 

 are like a jerkin and a jerkin's lining ; rumple the 

 one, and you rumple the other." 



I have now described to you as much of the 

 structure of the body, and its functions, as I con- 

 ceive to be necessary, in order to enable you to 

 understand what I have presently to say on the 

 subject of diet and regimen. And you must now 

 know quite enough to be heartily convinced of the 

 unmitigated folly of those persons, who, without 

 knowing any thing of the structure of living parts, 

 or of their actions, or of those delicate springs, 

 contractility and sensibility, which originate and 

 sustain those actions who, I say, being as ignorant 

 as idiotism of all that concerns the nature of life 

 and living things, are nevertheless perpetually 

 tinkering their stomachs with quack remedies ; 

 thus stupidly presuming to mend a machine, of the 

 very nature and structure and actions of which 

 they are as uninformed as infant Hottentots. 



The health of the body depends upon the healthy 

 performance of the nutritive actions; and disease 

 consists in the unhealthy performance of these 



