ON SCIENCE AND ART 147 



mentary teaching might be properly carried out by 

 teachers provided with only elementary knowledge. Let 

 me assure you that that is the profoundest mistake in 

 the world. There is nothing so difficult to do as to 

 write a good elementary book, and there is nobody so 

 hard to teach properly and well as people who know 

 nothing about a subject, and I will tell you why. If 

 I address an audience of persons who are occupied in 

 the same line of work as myself, I can assume that they 

 know a vast deal, and that they can find out the 

 blunders I make. If they don't it is their fault and not 

 mine; but when I appear before a body of people who 

 know nothing about the matter, who take for gospel 

 whatever I say, surely it becomes needful that I consider 

 what I say, make sure that it will bear examination, 

 and that I do not impose upon the credulity of those 

 who have faith in me. In the second place, it involves 

 that difficult process of knowing what you know so well 

 that you can talk about it as you can talk about your 

 ordinary business. A man can always talk about his 

 own business. He can always make it plain; but, if his 

 knowledge is hearsay, he is afraid to go beyond what he 

 has recollected, and put it before those that are ig- 

 norant in such a shape that they shall comprehend it. 

 That is why, to be a good elementary teacher, to' teach 

 the elements of any subject, requires most careful con- 

 sideration, if you are a master of the subject; and, if 

 you are not a master of it, it is needful you should 

 familiarise yourself with so much as you are called upon 

 to teach soak yourself in it, so to speak until you 

 know it as part of your daily life and daily knowledge, 

 and then you will be able to teach anybody. That is 

 what I mean by practical teachers, and, although the 

 deficiency of such teachers is being remedied to a large 

 extent, I think it is one which has long existed, and 



