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COORDINATION AND SENSATION 



between a candle and a screen in a dimly lighted room, a 

 position will bi found where a picture of the candle falls 

 upon the screen. This picture, called the image, results 

 from the refraction of the candle light in passing through 

 the lens. 



Image 



FIG. 158. Diagram illustrating formation of images. On the right 

 the image is formed by a double convex lens; on the left by the lenses of the 

 eye. The candle flame represents a luminous, or light-giving, body; but light 

 passes from the large arrow by reflection. (See text.) 



In order to form an image, the light waves spreading out from the 

 object must be brought together, or*focused. Focusing means literally 

 the bringing of light to a point, but it is evident in the formation of an 

 image that all the waves are not brought to a single point. If they 

 were, there would be no image. In the example of the candle given 

 above, the explanation is as follows : 



The light from the candle comes from a great number of separate 

 and distinct points in the candle flame. The lens, by its peculiar shape, 

 bends the waves coming from any single point so that they are brought 

 to a corresponding point on the screen. Furthermore, the points of 

 focused light are made to occupy the same relative positions on the 

 screen as the points from which they emanate in the candle flame 

 (Fig. 158). This is why the area of light on the screen has the same 

 form as the candle, or makes an image of it. The same explanation 

 applies if, instead of the luminous candle, a body that simply reflects 

 light, as a book, is used. 



The Problem of Seeing. What we call seeing is vastly 

 more than the stimulation of the brain through the action 

 of light upon afferent neurons. It is the perceiving of all 

 the different things that make up our surroundings. If 



