How Past Experience Is Conserved

PAST EXPERIENCE CONSERVED IN BOTH MENTAL AND PHYSICAL TERMS.--If past

experience plays so important a part in our welfare, how, then, is it to

be conserved so that we may secure its benefits? Here, as elsewhere, we

find the mind and body working in perfect unison and harmony, each doing

its part to further the interests of both. The results of our past

experience may be read in both our mental and our physical nature.

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On the physical side past experience is recorded in modified structure

through the law of habit working on the tissues of the body, and

particularly on the delicate tissues of the brain and nervous system.

This is easily seen in its outward aspects. The stooped shoulders and

bent form of the workman tell a tale of physical toil and exposure; the

bloodless lips and pale face of the victim of the city sweat shop tell

of foul air, long hours, and insufficient food; the rosy cheek and

bounding step of childhood speak of fresh air, good food and happy play.



On the mental side past experience is conserved chiefly by means of

images, ideas, and concepts. The nature and function of concepts

will be discussed in a later chapter. It will now be our purpose to

examine the nature of images and ideas, and to note the part they play

in the mind's activities.



THE IMAGE AND THE IDEA.--To understand the nature of the image, and then

of the idea, we may best go back to the percept. You look at a watch

which I hold before your eyes and secure a percept of it. Briefly, this

is what happens: The light reflected from the yellow object, on striking

the retina, results in a nerve current which sets up a certain form of

activity in the cells of the visual brain area, and lo! a percept of

the watch flashes in your mind.



Now I put the watch in my pocket, so that the stimulus is no longer

present to your eye. Then I ask you to think of my watch just as it

appeared as you were looking at it; or you may yourself choose to think

of it without my suggesting it to you. In either case the cellular

activity in the visual area of the cortex is reproduced approximately

as it occurred in connection with the percept, and lo! an image of the

watch flashes in your mind. An image is thus an approximate copy of a

former percept (or several percepts). It is aroused indirectly by means

of a nerve current coming by way of some other brain center, instead of

directly by the stimulation of a sense organ, as in the case of a

percept.



If, instead of seeking a more or less exact mental picture of my

watch, you only think of its general meaning and relations, the fact

that it is of gold, that it is for the purpose of keeping time, that it

was a present to me, that I wear it in my left pocket, you then have an

idea of the watch. Our idea of an object is, therefore, the general

meaning of relations we ascribe to it. It should be remembered, however,

that the terms image and idea are employed rather loosely, and that

there is not yet general uniformity among writers in their use.



ALL OUR PAST EXPERIENCE POTENTIALLY AT OUR COMMAND.--Images may in a

certain sense take the place of percepts, and we can again experience

sights, sounds, tastes, and smells which we have known before, without

having the stimuli actually present to the senses. In this way all our

past experience is potentially available to the present. All the objects

we have seen, it is potentially possible again to see in the mind's eye

without being obliged to have the objects before us; all the sounds we

have heard, all the tastes and smells and temperatures we have

experienced, we may again have presented to our minds in the form of

mental images without the various stimuli being present to the

end-organs of the senses.



Through images and ideas the total number of objects in our experience

is infinitely multiplied; for many of the things we have seen, or heard,

or smelled, or tasted, we cannot again have present to the senses, and

without this power we would never get them again. And besides this fact,

it would be inconvenient to have to go and secure afresh each sensation

or percept every time we need to use it in our thought. While habit,

then, conserves our past experience on the physical side, the image

and the idea do the same thing on the mental side.