In order to understand the amount of material available for use by the dream, it may be well for us to consider, briefly, some aspects of our mental life, particularly as regards the mind's retentiveness.

We may be said to possess three minds, namely the conscious mind, the fore-conscious mind, and the unconscious mind. At times the term subconscious mind is employed; it is synonymous with the unconscious mind. Of course, these divisions are made solely for explanatory purposes. The mind is intact, one structure. Anatomically we would be unable to locate the position of any of these minds, but such a division is very convenient for understanding various mental phenomena.

The conscious mind contains such thoughts as we are thinking of at this moment. In a day we think of many things; while we are thinking of these things the latter are conscious; they occupy the conscious mind; we are aware of them.

There are many things which we are not thinking of at this moment, but which we are able to think of -bring to the conscious mind. For example, we can recall the names of various friends, telephone numbers, places we have been, etc. Some of these things we can think of - make conscious - readily, possibly because we make frequent use of them, or because they made a great impression upon us. Others, probably for opposite reasons, are recalled less readily. For example, I may try to think of the name of a certain person I have met, but without immediate success. Then I think of the circumstances under which I met him, people he resembles, where he lives, etc., trusting that some of these things will suggest the name I am in quest of by association. Finally, something which has an association with the name brings the latter to mind. Though the memory was recalled slowly, the fact remains that I was able to recall it. Now all these things which I can recall must be present in some part of the mind when they are not in consciousness; and their comparative ease of recall makes it appear that they are not far from consciousness. It is in the fare-conscious mind, or pre-conscious, that they are stored. The fore-conscious mind contains therefore, all those ideas, tacts, images which we can recall voluntarily, whether readily or slowly; it is a repository for memories which, while not always in use, are available for consciousness, which can be summoned to consciousness whenever we wish to make use of them.

We have had, however, countless thoughts, countless experiences which, try as we may, we cannot voluntarily recall. For example, we saw many things and did many things in childhood, a very impressionable period, which, as far as recollection is concerned, may be said to have been entirely forgotten. Indeed, we need not go so far back; many experiences of last summer, last week even, are beyond voluntary recall. In various ways, as in dreams, delerii, anesthesia, we are led to believe that the mind forgets nothing; everything we see, hear, taste, think of, or experience in any other way leaves an indelible and distinct impression on the mind. It is in what we call the unconscious mind that the innumerable memories which we cannot make con-scious" voluntarily are stored. The unconscious1 is, therefore, the storehouse of what we call forgotten experiences. When we say forgotten we really "mean the inability to bring the experiences in question to consciousness.

As a rule, most of our experiences are conscious at first; we think of them for a longer or shorter time. Experiences, or thoughts, are constantly changing, however, so that the replaced thoughts become fore-conscious. Some experiences remain in the fore-conscious for a long time, even a lifetime, for the reason that they are called to consciousness often, as certain names; or because they have made a profound impression upon us, as a drowning or other serious accident. Other experiences pass rapidly or gradually to the unconscious mind because they are indifferent, or little used; because they have passed rapidly through consciousness without obtaining much recognition; or because they have been repressed. By repression is meant a resistance, an exercise of the will, whereby we refuse to allow certain thoughts to be entertained in consciousness. These thoughts are usually ones which are of a painful nature. By constantly refusing to think of them, after a time many of them pass into the unconscious mind. Though "out of mind" they are not banished, and indirectly exert an influence upon us.

An important point is that a sensation or experience may become fixed in the mind without the necessity of consciousness' paying attention to the sensation or experience. Countless sensations of which we are consciously unaware are constantly making impressions upon us. In this respect the mind may be compared to a camera plate or film. We survey a scene and various things attract our attention, and other things do not. Of course, if we studied a scene in detail we might observe many things which would escape casual observation, but even then we would overlook many things. Yet if we took a picture of this scene, we would find on developing the plate that every single thing which could possibly make an impression on the plate has been recorded. The mind is also a sensitive plate which records everything to which it is exposed. Its lenses, so to speak, are the senses, - the eyes, the ears, the nose, etc.; and these are constantly taking "pictures," whether we consciously realize it or not.

1 In a psychological sense, the word unconscious always means "not aware of"; ideas of which we have no conscious knowledge; which we cannot bring to consciousness voluntarily. An unconscious person is entirely oblivious of his surroundings, and his feelings; there is no mental perception.

The above mentioned point may be illustrated in many ways. For example, in daily life it is often noticed that a person, while absorbed in thought, in reading, or in a conversation, pays no attention apparently to a remark made by some one. However, a half-hour, more or less, later, he replies to the remark; and it seems to him that the remark he is replying to has just been made. Probably the idea the writer wishes to convey can be even better illustrated by using the words of Sally, one of the personalities of Miss Beauchamp, whose interesting case has been studied by Dr. Morton Prince.1 In speaking of dreams Sally says: