HUMAN PHYSIOLOGY, 



PROLEGOMENA. 



I. NATURAL BODIES. 



THE extensive domain of Nature is divisible into three great classes : 

 Minerals, Vegetables, and Animals. This division was universally 

 adopted by the ancients, and still prevails, especially amongst the un- 

 scientific. When, however, we carefully examine their respective cha- 

 racteristics, we discover, that the animal and the vegetable resemble 

 each other in many essential particulars. This resemblance has given 

 occasion to the partition of all bodies into two classes : the Inorganic, 

 or those not possessing organs or instruments adapted for the perform- 

 ance of special actions or functions, and the Organized, or such as 

 possess this arrangement. 



In all ages, philosophers have attempted to point out a 



"Vast chain of being, which from GOD began, 

 Nature's ethereal, human, angel, man, 

 Beast, bird, fish, insect, what no eye can see, 

 No glass can reach " 



the links of which chain they have considered to be constituted of all 

 natural bodies ; passing by insensible gradations through the inorganic 

 and the organized, and forming a rigid and unbroken series ; and in 

 which, they have conceived, 



" Each moss, 



Each shell, each crawling insect, holds a rank, 

 Important in the plan of Him who framed 

 This scale of beings holds a rank which, lost, 

 Would break the chain, and leave behind a gap 

 Which Nature's self would rue." 



Crystallization has been esteemed by them as the highest link of 

 the inorganic kingdom; the lichen, which encrusts the stone, as but 

 one link higher than the stone itself; the mushroom and the coral as 

 the connecting links between the vegetable and the animal ; and the 

 immense space, which separates man the highest of the mammalia 

 from his Maker, they have conceived to be occupied in succession by 

 beings of gradually increasing intelligence. If, however, we investi- 

 gate the matter minutely, we discover that many links of the chain 

 appear widely separated from each other; and that, in the existing 



VOL. I. 3 



