6-i HISTORY OF OPTICS. 



Gothe not only adopted and strenuously maintained the opinion that 

 the Newtonian theory was false, but he framed a system of his own to 

 explain the phenomena of color. As a matter of curiosity, it may be 

 worth our while to state the nature of this system ; although undoubt- 

 edly it forms no part of the progress of physical science. Gothe's 

 views are, in fact, little different from those of Aristotle and Antonio 

 de Dominis, though more completely and systematically developed. 

 According to him, colors arise when AVC see through a dim medium 

 ("ein triibes mittel"). Light in itself is colorless; but if it be seen 

 through a somewhat dim medium, it appears yellow ; if the dimness 

 of the medium increases, or if its depth be augmented, we see the 

 light gradually assume a yellow-red color, which finally is heightened 

 to a ruby-red. On the other hand, if darkness is seen through a dim 

 medium which is illuminated by a light falling on it, a blue color is 

 seen, which becomes clearer and paler, the more the dimness of the 

 medium increases, and darker and fuller, as the medium becomes more 

 transparent; and when we come to "the smallest degree of the purest 

 dimness," we see the most perfect violet." In addition to this " doc- 

 trine of the dim medium," we have a second principle asserted con- 

 cerning refraction. In a vast variety of cases, images are accompanied 

 by " accessory images," as when we see bright objects in a looking- 

 glass. 18 Now, when an image is displaced by refraction, the displace- 

 ment is not complete, clear and sharp, but incomplete, so that there is 

 an accessory image along with the principal one. 19 From these prin 

 ciples, the colors produced by refraction in the image of a bright 

 object on a dark ground, are at once derivable. The accessory image 

 is seinitransparent ; ao and hence that border of it which is pushed for- 

 wards, is drawn from the dark over the bright, and there the yellow 

 appears ; on the other hand, where the clear border laps over the 

 dark ground, the blue is seen ; 21 and hence we easily see that the image 

 must appear red and yellow at one end, and blue and violet at the 

 other. 



We need not explain this system further, or attempt to show how 

 vague and loose, as well as baseless, are the notions and modes of con- 

 ception which it introduces. Perhaps it is not difficult to point out 

 the peculiarities in Gothe's intellectual character which led to hia 

 singularly unphilosophical views on this subject. One important cir- 



IT 



Farbenlehre, 150, p. 151. le Ib. 223. 



18 Ib. 227. 20 Ib. 23 " Ib. 239. 



