62 NATURAL THEOLOar. 



is intelligible and certain ; that it is not the less so, because 

 it often begins or terminates with something which is not 

 mechanical ; that whenever it is intelligible and certain, it 

 demonstrates intention and contrivance, as well in the works 

 of nature as in those of art ; and that it is the best demon- 

 stration which either can afford. 



But while I contend for these propositions, I do not ex- 

 clude myself from asserting that there may be, and that there 

 are, other cases in which, although we cannot exhibit mech- 

 anism, or prove indeed that mechanism is employed, we 

 want not sufficient evidence to conduct us to the same con- 

 clusion. 



There is what may be called the chemical part of our 

 frame ; of which, by reason of the imperfection of our chem- 

 istry, we can attain to no distinct knowledge : I mean, not 

 to a knowledge, either in degree or kind, similar to that 

 which we possess of the mechanical part of our frame. Tl: 

 does not, therefore, afford the same species of argument Oi' 

 that which mechanism affords ; and yet it may afford an 

 argument in a high degree satisfactory. The gastric juice, 

 or the liquor which digests the food in the stomachs of ani- 

 mals, is of this class. Of all the m.enstrua it is the most 

 active, the most universal. In the human stomach, for in- 

 stance, consider what a variety of strange substances, and 

 how widely different from one another, it in a few hours 

 reduces to a uniform pulp, milk, or mucilage. It seizes upon 

 every thing; it dissolves the texture of almost every thing 

 that comes in its way. The flesh of perhaps all animals ; 

 the seeds and fruits of the greatest number of p'ij,nts ; the 

 roots and stalks, and leaves of many, hard and tough as they 

 are, yield to its powerful pervasion. The change wrought 

 by it is different from any chemical solution which w^e can 

 produce, or with which we are acquainted, in tliis respect as 

 well as many others, that in our chemistry particular men- 

 strua act only upon particular substances. Consider, more- 

 over, that this fluid, stronger in its operation than a caustic 



