A WORD OR TWO TOUDHING EVERY MAN*S MASTER. 275 



seated in his laboratory, surrounded with his retorts and alembicks, 

 may very correctly ascertain the proximate and ultimate principles of 

 animal and vegetable matter ; but when he comes to apply the know- 

 ledge thus acquired to the business of life, how vain are all his specu- 

 lations, and how limited his knowledge of digestion, or what is or is 

 not really digestible or nutritious. The inhabitants of the Polynesian 

 Islands, who live on fish, the supply of which is always precarious ; 

 the Esquimaux, who feast on blubber, and the Kamtscathdales, who 

 feed on fish oil, mixed up with the powdered bark of trees, to render 

 it more digestible, are all strong and robust, though living upon what 

 the dietetists pronounce indigestible and innutritious. Whilst the 

 Creek Indian, when entering upon a journey where the supply of 

 provisions is doubtful, fills his stomach with an indigestible clay,t 

 which, by the stimulus of distension alone, enables him to bear the 

 fatigues of his journey. Every work upon dietetics, from Fordyce 

 down to the latest and most popular one Dr. Paris, has run through 

 the animal and vegetable kingdom with the strictest chemical inquiry, 

 but all to little purpose. The chemical examination of diet, abstract- 

 edly considered, is of little importance ; the relative condition of the 

 digestive organs must always be considered in fixing a scale of 

 dietetics. 



Much of our knowledge in medicine and dietetics, like that in 

 every other art, proceeds on assumption that nature is always steady, 

 and that what was productive of certain effects in our constitution, 

 will be equally so in another ; but this applies less to the human body 

 than any other subject in nature to which art can be applied. The 

 laws of inorganic matter admit of the most correct inferences, whilst 

 the action and reaction of the various faculties of life increase the 

 difficulty and uncertainty of experiment and observation. Constitu- 

 tions are endowed with an endless variety of faculties, which must 

 ever render the result of medicine and dietetics, in their general appli- 

 cation, uncertain. Unless diversity of constitution be duly attended 

 to in the consideration of medical inquiries, we must often expose 

 ourselves to error, like those who made the contradictory report of 

 the chamelion. There is an observation made by Dr. Henderson, on 

 agricultural tracts, which is applicable to many of the works on 

 medical dietetics. " The inutility of publications on agriculture has 

 chiefly been owing to the authors not specifying clearly the nature of 

 the soil to which the practice recommended applies." The difficulties 

 of ascertaining the extent to which the operations of nature are limited 

 in the restoration of health is another fruitful source of error : such is 

 the impossibility of establishing where nature ends, and art begins. 



It is wonderful to think how readily we yield up our judgment and 

 reflection on matters which so intimately concern us, and upon which 

 experience and observation can alone furnish any grounds for know- 

 ledge, to men, who, big with their own speculations, and full of fine- 

 drawn theories, exclude from their list of dietetics all articles of diet 

 which do not agree with their chemical tests ; thus rendering a pre- 



f Humboldt's Travels. 



