58 NATURAL THEOLOGY. 



lives seen any but one single kind of hydraulic machine, yet 

 if of that one kind we understood the mechanism and use, 

 we should be as perfectly assured that it proceeded from the 

 hand and thought and skill of a workman, as if we visited a 

 museum of the arts, and saw collected there twenty different 

 kinds of machines for drawing water, or a thousand different 

 kinds for other purposes. Of this point each machine is a 

 proof independently of all the rest. So it is with the eviden- 

 ces of a divine agency. The proof is not a conclusion which 

 lies at the end of a chain of reasoning, of which chain each 

 instance of contrivance is only a link, and of which, if one 

 link fail, the whole falls ; but it is an argument separately 

 supplied by every separate example. An error in stating 

 an example affects only that example. The argument is cu- 

 mulative, in the fullest sense of that term The eye proves 

 it without the ear ; the ear without the eye. The proof in 

 each example is complete ; for when the design of the part, 

 and the conduciveness of its structure to that design is shown, 

 the mind may set itself at rest ; no future consideration can 

 detract any thing from the force of the example. 



