2 8o TEE POPULAR SCIENCE MONTHLY 



It can not be shown then that there was bitter warfare between sci- 

 ence and theology in the middle ages ; nor, on the other hand, was science 

 a handmaid at theology's beck and call. The two interests were begin- 

 ning to separate, sometimes with a little friction, often with much 

 caution on the part of science, yet on the whole with maintenance of 

 friendly relations between them. Science was still somewhat under the 

 wing of the church, but science was learning to use its own wings. 



Having traced back the scientific spirit in western Christian Europe 

 to the twelfth and thirteenth centuries rather than to the time of the 

 Italian Renaissance, let us now examine some of the particular fields 

 which it investigated. 



Physics was studied now, and not merely along the theoretical lines 

 of Aristotle's treatise. Further progress had been made among the 

 Arabs in optics; and the subjects of vision, perspective, reflection and 

 refraction were now better understood than in the time of Ptolemy. The 

 men of the thirteenth century speedily absorbed these new ideas of the 

 Arabs. Roger Bacon, it is true, while according due credit to the Arabs, 

 gives us the impression that his Latin contemporaries were neglecting 

 the subject of optics, and describes the formation of rainbows, and the 

 characteristics of convex and concave mirrors, burning glasses and 

 lenses by which the size of objects can be greatly magnified, or mirrors 

 by which their numbers can be greatly multiplied, as if all these things 

 were marvelous novelties. Bacon's own discussion of these matters is 

 excellent, and in some details he corrects or adds to his Arabian author- 

 ities, but he does not do justice to his Christian contemporaries. At just 

 about this time Witelo, a Pole who traveled in Italy, wrote an important 

 treatise on optics in which he embodied the views of Alhazen, the lead- 

 ing Arabian authority, together with many additions from other writers 

 and of his own. Moreover, the French "Romance of the Rose," prob- 

 ably written soon after Bacon's work, shows remarkable familiarity with 

 all the things that he describes. Of rainbows it remarks that 



Only he who's learned the rule 

 Of optics in some famous school 

 Can to his fellow men explain 

 How 'tis that from the sun they gain 

 Their glorious hues. 



The author also mentions burning-glasses and various other sorts of 

 mirrors, but he refers to all these as well-known scientific facts, and 

 says that there are plenty of books about them. He also unmistakably 

 describes magnifyng glasses when he tells us that from optics one 



. . . may learn the cause 

 "Why mirrors, through some subtle laws 

 Have power to objects seen therein 

 (Atoms minute or letters thin) 

 To give appearance of fair size, 



