168 LETTERS TO BROTHER JOHN. 



LETTER VI. 



224 Blackfriars Road, 



15th June, 1836. 

 MY DEAR JOHN, 



I HAVE now given you what I hope you have 

 found to be a tolerably clear notion of the intimate 

 structure that is, the ultimate tissue of the body 

 of the several actions concerned in nutrition 

 and of the nature of life and health. 



I have now to point out to you what I believe 

 to be the chief causes and sources of disease. 



When a man, who thinks as well as sees, suffers 

 his eye to range over the various minor systems 

 which compose the one great scheme of the uni- 

 verse when he looks at the planetary system, and 

 beholds worlds whirling amid worlds in countless 

 numbers, with inconceivable rapidity, yet infallible 

 precision when he dwells on the vegetable system, 

 and sees myriads of plants rising from the same 

 earth, living in the same air, warmed by the same 

 sun, watered by the same rain, yet each differing 



