GOETHE'S " FARBENLEHRE." 65 



that the silk formed a series of separate fine dark lines 

 upon the two coloured surfaces. He might have drawn 

 black lines over the red and blue, but the silk lines 

 were finer than any that he could draw. Illuminating 

 both surfaces, he placed a lens so as to cast an image of 

 the surfaces upon a white screen. The result was, that 

 when the dark lines were sharply defined upon the red, 

 they were undefined upon the blue; and that when, by 

 moving the screen, they were rendered distinct upon 

 the blue, they were indistinct upon the red. A distance 

 of an inch and a half separated the focus of red rays 

 from the focus of blue rays, the latter being nearer to 

 the lens than the former. Goethe appears to have at- 

 tempted a repetition of this experiment; at all events, 

 he flatly contradicts Xewton, ascribing his result not 

 to the testimony of his bodily eyes, but to that of the 

 prejudiced eyes of his mind. Goethe always saw the 

 dark lines best defined upon the brighter colour. It 

 was to him purely a matter of contrast, and not of 

 different refrangibility. He argues caustically that 

 Xewton proves too much; for were he correct, not only 

 would a dioptric telescope be impossible, but when pre- 

 sented to our naked eyes, differently-coloured objects 

 must appear utterly confusing. Let a house, he says, 

 be supposed to stand in full sunshine; let the roof -tiles 

 be red, the walls yellow, with blue curtains behind the 

 open windows, while a lady with a violet dress steps 

 out of the door. Let us look at the whole from a 

 point in front of the house. The tiles we will suppose 

 appear distinct, but on turning to the lady we should 

 find both the form and the folds of her dress undefined. 

 We must move forward to see her distinctly, and then 

 the red tiles would appear nebulous. And so with 

 regard to the other objects, we must move to and fro 

 in order to see them clearly, if Xewton's pretended 



