ALMOST everyone seems to think that we retain in the mind only those things that we can voluntarily recall; that memory, in other words, is limited to the power of voluntary reproduction.

This is a profound error. It is an inexcusable error. The daily papers are constantly reporting cases of the lapse and restoration of memory that contain all the elements of underlying truth on this subject.

It is plain enough that the memory seems decidedly limited in its scope. This is because our power of voluntary recall is decidedly limited.

But it does not follow simply because we are without the power to deliberately recall certain experiences that all mental trace of those experiences is lost to us.

Those experiences that we are unable to recall are those that we disregarded when they occurred because they possessed no special interest for us. They are there, but no mental associations or connections with power to awaken them have arisen in consciousness.

Things are continually happening all around us that we see with but "half an eye." They are in the "fringe" of consciousness, and we deliberately ignore them. Many more things come to us in the form of sense-impressions that clamorously assail our sense-organs, but no effort of the will is needed to ignore them. We are absolutely impervious to them and unconscious of them because by the selection of our life interests we have closed the doors against them.

In either case, whether in the "fringe" of consciousness or entirely outside of consciousness, these unper-ceived sensations will be found to be sensory images that have no connection with the present subject of thought. They therefore attract, and we spare them, no part of our attention.

Just as each of our individual senseorgans selects from the multitude of ether vibrations constantly beating upon the surface of the body only those waves to the velocity of which it is attuned, so each one of us as an integral personality selects from the stream of sensory experiences only those particular objects of attention that are in some way related to the present or habitual trend of thought.

Just consider for a moment the countless number and variety of impressions that assail the eye and ear of the New Yorker who walks down Broadway in a busy hour of the day. Yet to how few of these does he pay the slightest attention. He is in the midst of a cataclysm of sound almost equal to the roar of Niagara and he does not know it.

Observe how many objects are right now in the corner of your mind's eye as being within the scope of your vision while your entire attention is apparently absorbed in these lines. You see these other things, and you can look back and realize that you have seen them, but you were not aware of them at the time.

Let two individuals of contrary tastes take a day's outing together. Both may have during the day practically identical sensory images; but each one will come back with an entirely different tale to tell of the day's adventures.

All sensory impressions, somehow or other, leave their faint impress on the waxen tablets of the mind. Few are or can be voluntarily recalled.

Just where and how memories are retained is a mystery. There are theories that represent sensory experiences as actual physiological "impressions" on the cells of the brain. They are, however, nothing but theories, and the manner in which the brain, as the organ of the mind, keeps its record of sensory experiences has never been discovered. Microscopic anatomy has never reached the point where it could identify a particular "idea" with any one "cell" or other part of the brain.

For us, the important question is not how, but how much; not the manner in which, but the extent to which, sensory impressions are preserved. Now, all the evidences indicate that absolutely every impression received upon the sensorium is indelibly recorded in the mind's substance. A few instances will serve to illustrate the remarkable power of retention of the human mind.

Sir William Hamilton quotes the following from Coleridge's "Literaria Biographia": "A young woman of four- or five-and-twenty, who could neither read nor write, was seized with a nervous fever, during which, according to the asseverations of all the priests and monks of the neighborhood, she became 'possessed,' and, as it appeared, by a very learned devil. She continued incessantly talking Latin, Greek and Hebrew in very pompous tones, and with most distinct enunciation. Sheets full of her ravings were taken down from her own mouth, and were found to consist of sentences coherent and intelligible each for itself but with little or no connection with each other. Of the Hebrew, a small portion only could be traced to the Bible; the remainder seemed to be in the Rabbinical dialect." The case was investigated by a physician, who learned that the girl had been a waif and had been taken in charge by a Protestant clergyman when she was nine years old and brought up as his servant. This clergyman had for years been in the habit of walking up and down a passage of his house into which the kitchen door opened and at the same time reading to himself in a loud voice from his favorite book. A considerable number of these books were still in the possession of his niece.

Who told the physician that her uncle had been a very learned man and an accomplished student of Hebrew. Among the books were found a collection of Rabbinical writings, together with several of the Greek and Latin fathers; and the physician succeeded in identifying so many passages in these books with those taken down at the bedside of the young woman that there could be no doubt as to the true origin of her learned ravings.

Now, the striking feature of all this, it will be observed, is the fact that the subject was an illiterate servant-girl to whom the Greek, Latin and Hebrew quotations were utterly unintelligible, that normally she had no recollection of them, that she had no idea of their meaning, and finally that they had been impressed upon her mind without her knowledge while she was engaged in her duties in her master's kitchen.