52 LETTERS TO BROTHER JOHN. 



in the shape of perspiration and breath ; while the 

 deficiency thus produced in the eye has been sup- 

 plied by a part of yesterday's dinner ; so that you 

 are now performing the act of vision with a part of 

 the pudding which you ate at that meal. This is 

 not romance, nor speculation, but a literal fact. Is 

 not this, of itself, sufficient to shew you the vast 

 importance of the assimilating processes ? Does it 

 not clearly demonstrate to you the manner in 

 which faulty assimilation operates, so as to injure 

 the health and perfection of your organs ? Is it 

 not manifest, that if your assimilating organs do not 

 perfectly assimilate your food, that the deficiencies 

 produced in your eye, by the action of the absor- 

 bents, will be either not supplied at all, or supplied 

 with new matter, of an unhealthy quality ; so that 

 the new eye will not be so good and perfect as the 

 old one ? 



From considering the different functions which 

 the chylous and lymphatic absorbents perform, you 

 will readily understand why we grow in youth, and 

 cease to grow in manhood. It is because, in youth, 

 the chylous absorbents, which bring new matter 

 into the system, and the arteries, which convert this 

 new matter into flesh and blood, are more active 

 than the lymphatics ; while in manhood the activity 



