AND THE THEORY OF LIGHT. 33 



observations on black. After much supposition and con- 

 jecture, he adds: "And hence may be understood why- 

 blacks are usually a little inclined to a bluish colour. For 

 that they are so may be seen by illuminating white paper 

 by light reflected from black substances. For the paper 

 will appear of a bluish white ; and the reason is, that black 

 borders on the obscure blue of the first order described in 

 the eighteenth observation, and therefore reflects more 

 rays of that colour than any other.^' Newton has nowhere, 

 as far as I remember, told us how to perform this experi- 

 ment; and I confess I cannot understand how it can be 

 done without taking into account other light which must 

 be reflected from the paper. 



51. Few people, however, who have made any experi- 

 ments on light, can have failed to make an observation the 

 converse of that of Newton, namely, that white reflected 

 from black, in favourable circumstances or conditions, is 

 blue. Any one who has examined, for instance, the re- 

 flection of a white china plate on a black ground, as black 

 marble or black japan, must have remarked this, for it is 

 a very common phenomenon. The reflection of the white 

 object on the black ground is blue; but no one would 

 infer that a decomposition of the white light has taken 

 place because blue is reflected; it would rather be supposed 

 that, provided the light be sufficiently bright, the portion 

 of it which is reflected from the white china, when insulated 

 from the other portion, produces the observed effect on 



both to the active faculties, and to the passive capacities of mind." — Again 

 he says : " There is no pure activity, no pure passivity in nature. All 

 things in the universe are reciprocally in a state of continual action and 

 counteraction. . . . Activity and passivity are not, therefore, in the mani- 

 festations of mind distinct independent phenomena. This is a great, 

 though a common, error. They are always conjoined. There is no opera- 

 tion of the mind which is purely active, no affection which is purely 

 passive. In every mental modification, action and passion are the two 

 necessary elements or factors of which it is composed." — Lectures on 

 Metaphysics, i6th and 17th. 



SER. III. VOL. I. F 



