366 PHYSICAL SCIENCE IN THE MIDDLE AGES. 



But the existence of a course of instruction, and of 

 a body of rules of practice, is proved beyond dis- 

 pute by the great series of European cathedrals 

 and churches, so nearly identical in their general 

 arrangements, and in their particular details. The 

 question then occurs, have these rules and this 

 system of instruction anywhere been committed to 

 writing ? Can we, by such evidence, trace the pro- 

 gress of the scientific idea, of which we see the 

 working in these buildings? 



We are not to be surprized, if, during the most 

 flourishing and vigorous period of the art of the 

 middle ages, we find none of its precepts in books. 

 Art has, in all ages and countries, been taught and 

 transmitted by practice and verbal tradition, not by 

 writing. It is only in our own times, that the 

 thought occurs as familiar, of committing to books 

 all that we wish to preserve and convey. And, 

 even in our own times, most of the Arts are learned 

 far more by practice, and by intercourse with prac- 

 titioners, than by reading. Such is the case, not 

 only with Manufactures and Handicrafts, but with 

 the Fine Arts, with Engineering, and even yet, with 

 that art, Building, of which we are now speaking. 



We are not, therefore, to wonder, if we have 

 no treatises on Architecture belonging to the great 

 period of the Gothic masters ; or if it appears to 

 have required some other incitement and some 

 other help, besides their own possession of their 

 practical skill, to lead them to shape into a literary 

 form the precepts of the art which they knew so 



