738 THE POPULAR SCIENCE MONTHLY. 



through the mind, one crowding upon another ; and it is only 

 when we need to tell some one else about them that we use lan- 

 guage. Call up to your mind for a moment the place in which 

 you passed last summer, and already there has appeared a series 

 of mental images of place and people, of scenes and events, each 

 following the other with amazing rapidity but in silent succession. 

 Max Muller would have us believe that thought without words is 

 impossible, and he even attempts to trace the development of 

 thought by studying the growth of language.* But many authori- 

 ties, scientific and philosophical, teach the contrary, and rather 

 than accept his position one is tempted to undermine it by advanc- 

 ing the opinion that few men think as the student of words does. 



If we think, then, by means of mental images largely, it may 

 be worth while to study the structure of a mental image. 



When you examine a flower you perceive its graceful shape 

 and form, its exquisite color, its delicate fragrance, and its soft, 

 velvety feel. You say it is called a rose, but; — 



" What's in a name? That which we call a rose, 

 By any other name would smell as sweet." 



So that without its name you have a mental image of it, which is 

 made up of several distinct sensations. These are the sensations 

 of the rose as it appears to the eye — the visual image ; the sensa- 

 tion as it reaches the nose — the olfactory image ; and the sensation 

 of its touch, its shape, and softness — the tactile image. These im- 

 pressions on the different senses have been sent to distinct and 

 separate regions of the brain surface. There, having been re- 

 ceived, they are stored up, so that the image once formed can be 

 recognized when repeated and can be revived in memory. 



Every sensation leaves behind it a trace upon the brain, which 

 trace is the physical basis of our memory of the sensation. Per- 

 haps no modern conception of the physical basis of memory is 

 more graphic than that which we find in Plato. In the " Theaete- 

 tus " he puts the following words into the mouth of Socrates : 



" I would have you imagine, then, that there exists in the mind 

 of man a block of wax, which is of different sizes in different men, 

 harder, moister, and having more or less purity in one than in an- 

 other. Let us say that this tablet is a gift of Memory, the mother 

 of the Muses, and that when we wish to remember anything which 

 we have seen or heard or thought in our own minds, we hold the 

 wax to the perceptions and thoughts, and in that receive the im- 

 pressions of them as from the seal of a ring ; and that we remem- 

 ber and know what is imprinted as long as the image lasts ; but 

 when the image is effaced or can not be taken then we forget and 

 do not know/' f 



* " Science of Thought." f " Theaetetus," Jowett's translation. 



