PROGRESS OF THE ARTS. 353 



consider the matter strictly, a practical assumption 

 of a principle does not imply a speculative know- 

 ledge of it. 



We may, in another way also, show how in- 

 admissible are the works of the master Artists of 

 the middle ages into the series of events which 

 mark the advance of Science. The following maxim 

 is applicable to a history, such as we are here 

 endeavouring to write. We are employed in trac- 

 ing the progress of such general principles as 

 constitute each of the sciences which we are re- 

 viewing ; and no facts or subordinate truths belong 

 to our scheme, except so far as they lead to or 

 are included in these higher principles; nor are 

 they important to us, any further than as they 

 prove such principles. Now with regard to pro- 

 cesses of art like those which we have referred 

 to, as the inventions of the middle ages, let us ask, 

 what principle each of them illustrates? What 

 chemical doctrine rests for its support on the phe- 

 nomena of gunpowder, or glass, or steel? What 

 new harmonical truth was illustrated in the Gre- 

 gorian chant? What mechanical principle unknown 

 to Archimedes was displayed in the printing-press? 

 The practical value and use, the ingenuity and skill 

 of these inventions is not questioned; but what 

 is their place in the history of speculative know- 

 ledge? Even in those cases in which they enter 

 into such a history, how minute a figure do they 

 make ! how great is the contrast between their 

 VOL. i. A A 



