vii SCIENCE AND ART AND EDUCATION 171 



elementary teaching might be properly carried out 

 by teachers provided with only elementary know- 

 ledge. Let me assure you that that is the pro- 

 foundest 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 pro- 

 cess 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 ignorant in such a shape that they shall 

 comprehend it. That is why, to be a good elemen- 

 tary teacher, to teach the elements of any subject, 

 requires most careful consideration, if you are a 

 master of the subject ; and, if you are not a master 



