Page:Popular Science Monthly Volume 35.djvu/764

738 through the mind, one crowding upon another; and it is only when we need to tell some one else about them that we use language. 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 Müller 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 authorities, scientific and philosophical, teach the contrary, and rather than accept his position one is tempted to undermine it by advancing 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 sensation as it reaches the nose—the olfactory image; and the sensation of its touch, its shape, and softness—the tactile image. These impressions on the different senses have been sent to distinct and separate regions of the brain surface. There, having been received, 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. Perhaps no modern conception of the physical basis of memory is more graphic than that which we find in Plato. In the "Theætetus" 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 another. 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 impressions of them as from the seal of a ring; and that we remember 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."