OF HEALTH AND HUMAN NATURE. 47 



the solid organised substance of our bodies, while the food 

 requires various intermediate changes before it is capable of 

 affording nutriment ; the inosculation of the vessels formed in 

 extravasated blood and secreted lymph with those of surrounding 

 parts ; and finally the production of the genital fluids from the 

 blood itself ; do appear to me very strong arguments in favour of 

 the life of the blood. * I am inclined with Mr. Hunter to be- 

 lieve that the chyle is alive, and that vivification commences even 

 in the stomach, although I should be sorry to go the same 

 length with Albinus, who granted life even to the excrement. 

 For the excretions must be regarded as dead matter, useless and 

 foreign to the system ; and they all run with the greatest rapi- 

 dity into decomposition. In operating for retention of urine, 

 the surgeon finds this fluid abominably foetid ; the feces become 

 so when not discharged in due time ; and the neglect of washing 

 the surface is the source of filthiness and disease. 



The essential nature of life is an impenetrable mystery, and 

 no more a subject for philosophical inquiry than the essential 

 nature of attraction or of matter. To attempt explaining the phe- 

 nomena of life by a vital fluid is only increasing the intricacy of 

 the subject by an unfounded hypothesis, and always reminds 

 me of Mr. Dugald Stewart's remark, that " There is even some 

 reason for doubting, from the crude speculations on medical 

 and chemical subjects which are daily offered to the public, whe- 

 ther it (the proper mode of studying nature) be yet understood 

 so completely as is commonly imagined, and whether a fuller 

 illustration of the rules of philosophising, than Bacon or his fol- 

 lowers have given, might not be useful even to physical in- 

 quirers." f We see matter in a certain state possessed of a cer- 

 tain power which we term life, and the object of physiology is 

 merely to observe its effects, just as it is the object of chemistry 

 to observe the circumstances of the affinity of different bodies and 



* Consult Hunter's Treatise on the Blood, &c. P. i. ch. i. 



*T Elements of tliv Philosophy of the Human Mind. Vol. i. p. . 



