THE SIX GATEWAYS OF KNOWLEDGE. 285 



logic-chopping about the words here ; we seem 

 to define in a vicious circle. We may begin by 

 defining light " It is light if you see it as light ; 

 it is not light if you do not see it." To save 

 circumlocution, we shall take things in that way. 

 Radiant heat is light if we see it, it is not light 

 if we do not see it. It is not that there are two 

 things ; it is that radiant heat has differences of 

 quality. There are qualities of radiant heat 

 that we can see, and if we see them we call them 

 light ; there are qualities of radiant heat we cannot 

 see, and if we cannot see them we do not call 

 them light, but still call them radiant heat : and 

 that on the whole seems to me to be the best 

 logic for this subject. 



By the by, I don't see Logic among the 

 studies of the Birmingham and Midland Institute. 

 Logic is to language and grammar what mathe- 

 matics is to common sense ; logic is etherealised 

 grammar. I hope the advanced student in 

 grammar and Latin and Greek, who needs logic 

 perhaps as much as, perhaps more than, most 

 students of science and modern languages, will 



