14 INTRODUCTION. 



and extended. Extraneous substances penetrate 

 the body, and first become mixed or actually iden- 

 tified with the fluent liquid. This in its turn nou- 

 rishes or renovates the solids, by deposition of cer- 

 tain of its component particles, and also detaches 

 from the solids such of their parts as, having per- 



things, can account for the nature or origin of the phenomena to 

 which they relate ; for, however me may substitute terms, or mul- 

 tiply illustrations, we cannot explain the changes which conti- 

 nually take place in living bodies, by means of the laws and affi- 

 nities which characterize the combinations of inorganized matter. 

 Such, therefore, being the case, we are justified in recurring to 

 the belief in a vital principle which, allied to matter, controls its 

 changes and forms, and to which principle the laws arid affinities 

 of inanimate matter are entirely subject. By means of such a su- 

 perior influence we are enabled to explain the phenomena of the 

 organized creation, but without its assistance we are lost in the 

 mazes of vague hypothesis and groundless supposition. 



2d. It has been objected to the existence of such a principle, 

 that we cannot demonstrate it to the senses, in a form unconnected 

 with matter. But we are not contending for the existence of a 

 principle which is material, according to the received notions re- 

 specting matter, therefore it is no evidence of the non-existence of 

 such a principle that it does not become visible to our senses, in 

 an uncombined form ; it is, however, sufficiently demonstrable in 

 its effects, in alliance with matter, in which state it presents proofs 

 of its being equal to those from which we infer the existence of 

 matter itself. 



3d. In order to explain the phenomena which are more justly 

 ascribed to a vital principle, the favourers of organism, — amongst 

 whom we can scarcely rank Cuvier,as we have already observed — 

 have recourse to the substitution of terms, to occult qualities, toirn- 

 pulses, to motions, &c. ; and when required to show wherein such 

 qualities, impulses, and motions, are different from the qualities, im- 

 pulses, and motions which are subjected to our experience, they en- 

 deavour to rid themselves of the difficulty by denominating them 

 vital, as if such a denomination were not a tacit admission of the very 

 principle, in the place of which such insufficient properties are at- 



