An amusing example of the everyday kind of forgotten experience occurred during the writing of this chapter.  I wrote a sentence which pleased me very well.  This is the sentence:  “In the esthetic processes of evolution they [man’s desires] have sunk below the surface as soon as formed, and have been covered over by an elastic and snug-fitting consciousness as the skin covers in the tissues and organs of the body.”  After showing this passage to my collaborator and remarking that this figure had never been used before, I was partly chagrined and partly amused to have her bring me the following sentence from White and Jelliffe:  “Consciousness covered over and obscured the inner organs of the psyche just as the skin hides the inner organs of the body from vision.”  My originality had vanished and I was close to plagiarism.  Indeed, if a history of plagiarism could be written, it would probably abound in just such stories.  I had read the article containing this sentence only once, about three years before, and had never quoted it or consciously thought of it.  It had lain buried for three years, only to come forth as an original idea of my own.  Who knows how many times we all do just this thing without catching ourselves in the trick?

=Back-Door Memories.= There are other kinds of memories which hide in the subconscious, memories of experiences which have not come in by the front door, but have entered the mind during special states, such as sleep, delirium, intoxication, or hypnosis.  What is known as post-hypnotic suggestion is the functioning of a suggestion received during hypnosis and emerging later as an impulse without being recognized as a memory.  A man in a hypnotic state is told that at five o’clock he will take off his clothes and go to bed, without remembering that such a suggestion has been given him.  He awakens with no recollection of the suggestion, but at five o’clock he suddenly feels impelled to go to bed, even though his unreasonable desire puts him into a highly embarrassing position.  The suggestion, to be thus effective, must have been conserved somewhere in his mind outside of consciousness.

Suggestions that enter the mind during the normal sleep are also recorded,—­a fact that carries a warning to people who are in the habit of talking of all sorts of matters while in the room with sleeping children.  I have sometimes suggested to sleeping patients that on waking they will remember and tell me the cause of their symptoms.  The following example shows not only the conservation of impressions gained in sleep, but also the sway of forgotten ideas of childhood, still strong in mature years.  This young woman, a trained nurse, with many marked symptoms of hysteria, had been asked casually to bring a book from the Public Library.  She cried out in consternation, “Oh, no, I am afraid!” After a good deal of urging she finally brought the book, although at the cost of considerable effort.  Later, while