In a discussion of attention the question of the relation of interest to attention is bound to arise. Do we attend to things because they are interesting? Or are we interested in things because we give them our attention? The two terms are so interwoven in meaning that they are frequently treated under one chapter heading. Our purpose here is not to attempt to divorce them, but rather to give them emphasis because of their significance in the teaching process. Attention denotes a focusing of mental energy on a particular idea or object; interest, subjectively considered, is an attitude of mind. Perhaps we can get a clearer idea of the two terms if we consider the various types of attention. First of all there is what is called _Involuntary_ attention. This is the type over which the mind has little or no control. A person sits reading--his attention fixed on the page in front of him--when suddenly a rock crashes through the window immediately behind him. He jumps to see what is wrong. His attention to his book is shifted to the window, not because he wills it so, but because of the suddenness and force of the stimulus. The excitation of the auditory nerve centers compels attention. The attendant feeling may be one of pleasure or of pain--there may be an interest developed or there may not. Involuntary attention clearly does not rest upon interest. Then there is what is called _Nonvoluntary_ attention. I go to a theatre and some particular musical number is featured. It grips my interest and I follow it with rapt attention, wholly without conscious effort. Unlike the case of a sudden noise, in this experience my attention is not physiologically automatic--I could control it if I chose--but I choose now to give it. Interest clearly is the motor power behind such attention. Then, finally, there is _Voluntary_ attention. I sit at a table working out a problem in arithmetic. Outside there is being played a most exciting ball game. My interests are almost wholly centered in the outcome of the game, but duty bids me work out my problem. I make myself attend to it in spite of the pull of my natural interests.