PROPERTIES OF LENSES. 21 



Professor Abbe goes on to say " and cannot be in- 

 terpreted as Morphological but only as Physical 

 characters, not as images of material forms but as 

 signs of material differences in the nature of the 

 particles composing the object, so that nothing more 

 can safely be inferred from the image as presented 

 to the eye, than the presence in the object of such 

 structural peculiarities as will produce the particular 

 diffraction phenomena, on which the images de- 

 pend." 



Unfortunately Professor Abbe has tacitly granted 

 the accuracy of the general idea of dioptric vision, 

 in order to throw his own discovery into greater pro- 

 minence; consequently in a recent address the whole 

 stress has been laid upon the fact that these images 

 are not exact representations of material forms. The 

 author must either have been blinded by association 

 and inherited materialism, or have been ignorant of 

 the fact that the same thing was proved with regard 

 to all images many years ago ; namely that nothing 

 more can safely be inferred from the image presented 

 to the eye, than the presence in the object of such 

 structural peculiarities, as will produce the particular 

 refraction phenomena on which the image depends. 



Almost all scientists are misled by the error of 

 conceiving material things to exist apart from the 

 mind that perceives them, (we by no means wish to in- 

 fer that their esse is a mere percipi). This confusion of 

 ideas has justly caused Hegel to remark "the English 

 are that nation in Europe which like the Huckster 

 and W orkman Class of the state are destined to pass 



