LETTERS TO BROTHER JOHN. 265 



of the two sorts of blood contained in the body, 

 &c. &c. By the way, all the subjects are not em- 

 braced in those three Letters; but, as it is abso- 

 lutely necessary that all these should be well under- 

 stood before you can clearly comprehend the full 

 force of what I am now going- to say, you had 

 better carefully re-peruse the whole, before you 

 proceed further. 



Supposing, then, that you have done this, and 

 done it understandingly ; and supposing that you 

 assent to the several definitions which I have given 

 of life, health, nutrition, contractility, sensibility, 

 stimuli, &c. ; and supposing that you see no reason 

 to doubt the accuracy of my statements relative to 

 the offices performed by the absorbents, secreting 

 glands, circulation of the blood, &c.; I now proceed 

 to point out to you my reasons for recommending 

 EXERCISE as a talismanic agent in the prevention 

 and cure of disease ; entreating you always to re- 

 member, that by disease I here mean solely that 

 depreciated state of the living actions that sickly 

 condition of the body in which there is no struc- 

 tural lesion of the organs in which no single organ 

 is affected by any accidental disorganization, or de- 

 nned and denominated disease but in which all 

 the nutritive actions are feebly performed, and in 



