May 5, 1916] 



SCIENCE 



623 



student understands perfectly. But, is it 

 our object to train him to understand state- 

 ments made by otliers — does ability to do 

 that constitute a knowledge of chemistry, 

 and play an important part in making a 

 chemist? Is a watchmaker a person who 

 recognizes a watch when he sees it, who 

 knows what makes it run, and when it is 

 running well, or is he a man who can make 

 and repair a watch ? Is not a chemist one 

 who can himself make correct statements 

 about chemical topics, and can himself put 

 together the necessary facts and ideas, and 

 himself reach a sound chemical conclusion ? 

 Listening to a lecture keeps the student in 

 a receptive attitude of mind, whereas the 

 attitude we desire to cultivate in him is the 

 precise opposite of this. The student 

 should begin by himself acquiring the 

 ability to state simple ideas correctly, and 

 later himself practise putting facts and 

 ideas together and reaching conclusions. 

 The conclusions are not new, but going 

 through the operation of reaching them for 

 himself is new to the student. No one 

 would explain to a group of people who 

 were not musicians how the piano is played, 

 and perform a few lecture experiments on 

 the piano, and then be foolish enough to 

 expect the audience to be able at once to 

 play the same pieces themselves. Of course 

 not, because we all know that every kind 

 of mechanical dexterity has to be acquired 

 by practise and by the formation of habits, 

 nervous and muscular. But we do not all 

 realize that mental operations are also 

 largely mechanical. For the most part 

 they are made up of half -unconscious re- 

 sponses, each of which is an idea previously 

 acquired by practise, and only the selection 

 of the units of which the whole mental 

 operation consists and the arranging of 

 them in due order are the results of actual 

 thought and conscious reasoning. After 

 explaining some point to the class, such as 



the reasons in terms of the ion-product 

 constant for the precipitation of calcium 

 oxalate, one might assume that they all 

 understood the explanation, and perhaps 

 they all do. But ask them individually to 

 state briefly the reason for the precipita- 

 tion, and some will make remarks that 

 have no bearing on the subject, some will 

 make partly incorrect statements, many 

 will make statements that are correct so 

 far as they go, but are incomplete. Only 

 one student in thirty will give a correct 

 and complete answer. Many of the others 

 undoubtedly understand the matter per- 

 fectly, but unless they have an oppor- 

 tunity themselves to put the answer to- 

 gether, the impression will be slight and 

 fleeting. It is the exercise of going through 

 the reasoning and the wording of the an- 

 swer, for oneself, that alone can make the 

 impression a permanent one and fix the 

 explanation in the mind. 



Evidently, the pupil would better study 

 the subject in the book, taking much or 

 little time according as his powers of acqui- 

 sition are slow or fast, until he can state 

 each important point in his own words. 

 Then the class-room work can be confined 

 to testing the preparation, discussing diffi- 

 culties, showing illustrative experiments, 

 and asking questions about the cases illus- 

 trated. Before printing was invented, oral 

 instruction was necessary. It seems to me 

 that a good many university men have not 

 yet realized that the printing press is now 

 available. It is right that we should know 

 the history of our profession, but not nec- 

 essary to adhere to all the practises of an- 

 tiquity. We all know walking was in- 

 vented before the locomotive, but none of 

 us walked to Urbana to this meeting. "Was 

 that thoroughly consistent? 



I am not proposing to abolish lecturing. 

 In courses taken by students who already 

 know how to study, that is, in the more 



