YOU have learned that Dissociation is a mental principle and process complementary to Association. Just as Association binds together the facts of experience into groups and complexes, so Dissociation selects for immediate emphasis and attention certain groups, certain ideas, certain elements, and causes others to be ignored so completely as apparently to be discarded altogether.

Those seemingly discarded are not permanently lost. They are merely thrust aside as of no immediate interest or consequence.

In brief, all the facts of experience fall into one or the other of two broad classes: first, those that are active in the present momentary state of consciousness; second, those that are inactive and subconscious.

And this latter class may again be subdivided into two classes: first, those that are ordinarily capable of voluntary recall; second, those that are as a rule beyond reach.

There is no hard-and-fast line to be drawn between these various divisions. They melt into one another by imperceptible degrees. They even change from day to day.

Some facts of experience are for a time so active as to be continually-thrust forward into consciousness, even against our will, "so that we can think of nothing else," but within a week we cannot for the life of us remember what they were. A popular air gets to "running through our heads," and for a day we sing it, we hum it, we whistle it, until our friends are no more tired of hearing it than we are, and in a week we try to recall the name of the song and it has slipped our memory.

Other experiences are so closely bound up with our present interest and activities that we can call them forth at any moment without appreciable effort. Still others come "to mind"- that is, to our consciousness - only with hard "thinking." Many utterly defy our efforts to recall them at all.

And beyond all there is a limitless volume of sense-impressions to which we have never given even a passing thought, which we have never even perceived when they occurred, of which we have never at any time been conscious, which would perhaps fail of recognition, even if recalled, which would seem to us a sort of mysterious forecast rather than a memory, and yet which constitute altogether by far the greater part of our experiential life.

We want you to do more than merely grasp the sense of these paragraphs. We want you to comprehend their present significance to you: We want you to feel, to know, that your mind is this vast and complex mechanism. We want you to picture to yourself your mind at this moment as the repository of all your past experience.

Just what facts of experience shall be dissociated and shunted off into inactivity and forgetfulness, what ones shall receive some slight passing notice, and what ones shall be emphasized and dwelt upon in consciousness to the exclusion of all else - all this is determined by Interest and Attention.

Now, attention may be conscious or unconscious; it may be voluntary or involuntary. It is regulated not so much by the will, as commonly understood, as by desire, conscious or unconscious. It is the creature of self-interest. Whatever is related to your interest in life, as you see it, receives your attention. Whatever receives your attention is emphasized while in consciousness, and is afterwards kept close at hand in subconsciousness ready for use.

Desire, interest, and will, then, set the dial of attention. Attention sounds the gong that marks certain elements of experience for special emphasis. Meanwhile the myriad other facts of experience not so particularly designated are dissociated from the important ones and busily stored away in less convenient archives.