APPENDIX 197 



about four hours, but to understand what it suggests 

 takes three or four weeks. Practically only two things 

 are to be seen, many transparent globules and definitely 

 arranged lines which enclose the globules. A young 

 student sees these things and can make a very creditable 

 picture of them, but if he is questioned it will be found 

 that his idea of the meaning of his sketch is very hazy. 

 He should not be forced to go on, then, until his difficul- 

 ties have been cleared away and the suggestiveness of 

 the section has been exhausted. 



He may know, in a general way, that the potato con- 

 tains starch and that cells are to be seen with the help 

 of the compound microscope. But it is fatal to a real 

 interpretation of what he sees if he is allowed to use 

 these words before he is sure of their meaning, for he 

 is apt to use them indiscriminately. It is much better 

 for him to use some non-technical word in the beginning 

 that simply describes what he sees. It matters very 

 little if he calls the cell walls, lines, and the starch 

 grains, globules, if he is able to find out for himself that 

 the lines are the walls of a box that enclose the globules 

 and that both lines and globules are insoluble solids. 

 The premature use of a word or a phrase to clothe an 

 idea that is not perfectly clear means the raising of a 

 barrier which may entirely prevent or indefinitely delay 

 perfect understanding. It is often wise to use a cir- 

 cumlocution to express an idea until one is sure of 

 using the word without losing sight of the thought. 

 Carelessness in the use of words results in such very 

 absurd ideas and .so much is gained in mental power 

 by accuracy in using them that it is surprising to find 



