Mind, my mind and yours, seems to have an intermittent and interrupted existence. Sleep, fainting, and other so-called "unconscious" conditions occupy large periods of the mind life of each one of us. Does it follow that mind and mental activity have no existence during these periods?

As a matter of fact we know that the vital operations of the body are conducted with as much precision and efficiency during sleep as when we are fully awake. May we not suspect that other mental processes are carried on without our conscious knowledge during the "unconscious state"? May they not occur under these circumstances just as they took place without our knowledge in the examples of absent-mindedness, absorption and preoccupation that we have been considering? Certainly this might happen and none could be the wiser.

How often do we lie down for a nap of an afternoon and seem unable to fall asleep. After what seems but a few minutes of fitful dozing, we decide to give up trying to go to sleep, and are told, to our astonishment, that we have really been sleeping for an hour or two. Nothing but a look at the clock will afterwards convince us that we have really slept. Was the mind active during this unconscious interval as well as before and after? Certainly consciousness was interrupted, and if any mental operations were performed, they were of a subconscious character. Let us see what the facts show.

In the first place, whenever you fall asleep, there is always a first stage of "dozing off." Now, if you are gently aroused from this state, you will find that you are always in the middle of a dream, and you can trace its origin by a series of associations to your last conscious sense-impressions.

Again, suppose that after living in the country for some time, you move to the city and occupy a room in a downtown hotel. Your first night, with its multitude of unaccustomed noises, will bring you little repose. Yet, after a year of living in the same place, you will sleep as sweetly to the tune of street-cars, wagons and electric pianos as ever you did in the silence of the hills.

That the senses are less acute in sleep than when we are awake may be admitted. But when we are once asleep, they are just as sharp or just as torpid at the end of the year as they were on that first distressful night.

Why is it, then, that you were annoyed on the first night, but were not disturbed by the same noises some months later? The noises, the physical surroundings, are the same; the change, then, is not in the physical world, but is in your own mind and its activity.

Clearly, the difference is identical with that we observed in the waking state as distinguishing the relaxed state of mind from that of preoccupation.

Suppose, for the sake of argument, that the mind does sleep with the body. Evidently the sleep of mind and of senses would be just as profound on the first night as on the last, and we would be unable to explain the first night's wakefulness.

It is plain, therefore, that the mind does not sleep like the body. Some element of the mind remains awake.

It is a discriminating element. On the first night this discriminating faculty of mind, made uneasy by unusual impressions, kept arousing consciousness to investigate; while on the last night, profiting by the lessons of experience, this discriminating faculty received these habitual and uninteresting impressions with tranquillity and left consciousness to its slumber.

The same explanation accounts for the discrimination shown in sleep by those who nurse the sick and by the mothers of young babies. All other, even tumultuous, noises may be ignored, but let the patient groan or even breathe heavily, or let the infant whimper, or even stir restlessly in bed, and instantly the nurse or mother is fully awake.

In the same way, many people have, to a remarkable degree, the faculty of measuring, during sleep, the flight of time. They are able to awaken at any given hour by simply making a firm resolve before retiring. Most persons habitually waken at the same time every morning. Indeed, the mind seems to measure the passage of time during sleep far more accurately than during the waking consciousness.

Is this possible unless there be mental activity during sleep? Does it not indicate that a watchful and discriminating faculty, call it attention, call it what you will, remains to guard the mind of consciousness from all disturbing sensory images excepting those which record the flight of time?

From the foregoing we must conclude that during sleep the senses deliver at least blurred impressions to some discriminating faculty of the mind; that this discriminating faculty of the mind passes judgment on these messages; that it arouses us to full and wakeful consciousness only if the impressions be painful or surprising, or the sign of some external fact toward which the mind is in an attitude of expectant attention; that despite all this mental activity no one would contend that we are conscious during sleep, that sleep is, therefore, a state of subconscious mental activity.

Here again, then, we have one more item added to the list of mental activities, energies and resources that are undreamed of in the average man's philosophy. There are, in fact, two features in all this that we would like to have stand out in your thought with particular clearness. One is what must be for you the ever-widening horizon of your own mentality. The other is the process by which consciousness, the mind that governs our outward lives, is made up of such elements as attention selects for it.

Mark these important conclusions. Somehow and somewhere the mind retains the impress of all past experiences. Many are constantly being employed in our active, conscious mental life. Far the greater part are stored in the great reservoir of subconsciousness. Some are subject to voluntary recall; others are there, but are said to be "forgotten." They may be recalled by an exaltation of the memory, but for the moment are out of mind, because in the course of events our interests have changed and these so-called "forgotten" experiences are not related by any association of ideas with the subject of our present thought.

This subconsciousness is a reservoir of ideas, emotions and motor impulses bound into groups by similarities and contiguities of time, space and the like. These groups are in turn linked together by common elements into systems termed complexes. This subconsciousness is a reservoir of unfathomable depth; consciousness is but a passing ripple upon its surface.

As our personal interests change with the exigencies of life, we correspondingly adjust the processes of attention and association on behalf of these interests. So it comes about that upon interest and attention depends the character of what we are able to recall, and upon the intensity and variety and complexity of our associations depends the quantity. Upon the reasonable cooperation of all these influences, together with the unfailing recognition of the past as past, depend the preservation of our normal mental life and our ability to appropriate and utilize to the highest degree for present needs the lessons of experience.

In all forms of "thinking," from the most listless reverie to the most intense volitional reasoning, association holds sway as the determining factor in the process. The only difference is that in reverie the attention swings freely from subject to subject at the instance of the passing whim, while in volitional reasoning to a desired conclusi«n, the will of the reasoner holds the attention steadfastly to those elements that it is desired to emphasize. The ones thus emphasized are in this way made the points of association, the common factors, with which the next idea must accord and to which it must relate. It thus appears that, by controlling the attention we can direct the associative processes and compel them to our will.

Attention is the holding in consciousness of a thought complex, either alone or in company with others.

Concentrated attention is exclusive attention to a single thought complex.

Concentration is an intense form of attention. If other subjects arc allowed to enter consciousness, concentration may weaken into merely casual interest. The degree of concentration depends upon the extent to which all outside interests are inhibited.

Concentration of the attention may be continuous, as when you give exclusive attention for a time to the solution of some problem or the completion of some task. It may be intermittent, as when through several years you strive to accomplish some great financial undertaking. Consciousness is here repeatedly focused or concentrated upon related details of the same project.

To concentrate is to bar every interest but the one interest.

No man can continuously concentrate his attention for any great length of time. But remember this: If you are to have a successful business career, you must have some one great interest inspired by the idea of financial success, some ruling passion, that shall persistently hold sway.