194? DISCOURSE ON THE STUDY 



after all, the acting cause in this process is nothing 

 more than a few gallons of water boiled in an iron 

 vessel, at a distance from the scene of operations. 

 But why the water so boiled should be capable of 

 producing the active energy which sets the whole 

 apparatus in motion is, and will probably long 

 remain, a secret to us. 



(206.) This, however, does not at all prevent our 

 having a very perfect comprehension of the whole 

 subsequent process. We might frequent printing- 

 houses, and form a theory of printing, and having 

 worked our way up to the point where the mechanical 

 action commenced (the boiler of the steam-engine), 

 and verified it by taking to pieces, and putting toge- 

 ther again, the train of wheels and the presses, and by 

 sound theoretical examination of all the transfers of 

 motion from one part to another ; we should, at length, 

 pronounce our theory good, and declare that we 

 understood printing thoroughly. Nay, we might 

 even go away and apply the principles of mechanism 

 we had learned in this enquiry to other widely 

 different purposes ; construct other machines, and 

 put them in motion by the same moving power, 

 and all without arriving at any correct idea as to 

 the ultimate source of the force employed. But, 

 if we were inclined to theorize farther, we might 

 do so ; and it is easy to imagine how two theorists 

 might form very different hypotheses as to the origin 

 of the power which alternately raised and depressed 

 the piston-rod of the engine. One, for example, might 

 maintain that the boiler (whose contents we will sup- 

 pose that neither theorist has been permitted to 

 examine) was the den of some powerful unknown 



