198 PHYSIOLOGY 



how little attention is paid to this phase of school work. 

 A new word is often learned before the idea which it 

 embodies is fully grasped, or the idea slips away, and 

 the word comes to be substituted for the idea. It is then 

 used at random, singly or associated with other words in 

 catch phrases, without a vestige of the underlying mean- 

 ing in the mind. 



Such simple words as solid, liquid, gas, heat, com- 

 bustion, chemical, physical, etc., are often used with so 

 little understanding of their real meaning, that one is 

 blinded to perfectly obvious relations. A word is sup- 

 posed to be the sign of an idea, but words are often used 

 to cover up a dearth of ideas. Even the wisest of us 

 is apt to fall into this shiftless habit, and it is no mean 

 offense, for it is a sign that one is falling into a lazy 

 habit of mind. It means finally the loss of mental alert- 

 ness and the joy of using one's own mind, which, after 

 all, is one of the greatest joys one can have. 



Even at the risk of being too diagrammatic it is 

 sometimes worth while to put the ideas that very simple 

 words stand for in a form which can be readily 

 visualized. By visualizing the meaning of the long 

 familiar word heat, for example, it may be made to 

 assume a new force and to bring ideas which have been 

 hazy or unconnected into a logical and definite relation. 

 Heat transference, expansion, evaporation, should not 

 be isolated ideas, but very definite corollaries of the 

 fact that matter is made of molecules which move and 

 have spaces between them. A pupil may understand 

 such a series of ideas and yet not be able to apply 

 them to the . explanation of even simple phenomena. 



