AND MODERN PHYSICS. 71 



that it requires exertion and involves fatigue, but we are con- 

 fident that if we only work hard our progress will be certain. 



"Some of us, on the other hand, may have had some 

 experience of the routine of experimental work. As soon as 

 we can read scales, observe times, focus telescopes, and so on, 

 this kind of work ceases to require any great mental effort. 

 We may, perhaps, tire our eyes and weary our backs, but we 

 do not greatly fatigue our minds. 



" It is not till we attempt to bring the theoretical part of 

 our training into contact with the practical that we begin to 

 experience the full effect of what Faraday has called ' mental 

 inertia* not only the difficulty of recognising, among the 

 concrete objects before u, the abstract relation which we have 

 learned from books, but the distracting pain of wrenching the 

 mind away from the symbols to the objects, and from the 

 objects back to the symlx>ls. This, however, is the price we 

 have to pay for new ideas. 



"But when we have overcome these difficulties, and 

 successfully bridged over the gulph between the abstract and 

 the concrete, it is not a mere piece of knowledge that we have 

 obtained ; we have acquired the rudiment of a permanent 

 mental endowment. When, by a repetition of efforts of this 

 kind, we have more fully developed the scientific faculty, the 

 exercise of this faculty in detecting scientific principles in 

 nature, and in directing practice by theory, is no longer irk- 

 some, but becomes an unfailing source of enjoyment, to which 

 we return so often that at last even our careless thoughts 

 begin to run in a scientific channel 



" Our principal work, however, in the Laboratory must be 

 to acquaint ourselves with all kinds of scientific methods, to 

 compare them and to estimate their value. It will, I think, 

 be a result worthy of our University, and more likely to be 

 accomplished here than in any private laboratory, if, by the 

 free and full discussion of tho relative value of different 

 scientific procedures, wo succeed in forming a school of 

 scientific criticism and in assisting the development of the 

 doctrine of method. 



44 But admitting that a practical acquaintance with the 



