Five groups of nerves connect the brain with the outside world, these are the five senses. They are the avenues of approach over which all impressions or sensations are conducted to the brain.
The ease with which any impression can be recalled will depend,—first, upon how strongly it is made.
Your senses are unequal in their ability to impress the brain. Some make stronger impressions than others, not so much because of the thing to be impressed, but because of the natural unequal strength of the groups of nerves. All experience or knowledge that makes a strong, definite impression is more easily recalled than in those cases where the impression is less distinct.
Nature has endowed one of the senses with a peculiar ability to make impressions upon the brain which are many times stronger than those made by any of the others. To learn to properly use this one sense is the greatest aid to memory improvement.
The Strongest Sense Is Sight
The nerves connecting the eye with the brain are many times larger than the nerves of any of the other sense organs and can make an impression which is many times stronger than the impression made by any of the others. Without your conscious knowledge this fact has been operating all your life. The things which you have seen are the things which you have most easily remembered. For this reason the memory of your youth consists principally of things which you saw, or impressions made upon your brain by the use of your eye.
Prove this fact; recall some of your earliest recollections; how did your brain accept these impressions? Was it through feeling, hearing, or through seeing? It is an eye impression and is recalled in your mind as a picture. You will find that most of the past which you can remember is based upon the visual impression. The poet says, "How dear to my heart are the scenes of my childhood." The scenes of childhood are the memory of childhood.
"Travel is the greatest of educators." Why? One reason is because you are gathering a group of eye impressions which are the most lasting. One psychologist defines memory, "as the act of recalling the picture of a past experience." The fact that the visual memory is most lasting has been known for generations, but we have failed to take proper advantage of the fact. In making a comparison of the eye and ear impressions upon the brain Robert Mudie wrote in 1832: "That which is told us we may forget because of the weakness of the impressions made, but that which we see with our own eye is proof against accident, against time and forgetfulness."