In an ordinary case there is great difficulty in persuading the man to talk about his war experiences: he says plainly that he doesn't want to talk about them, or may persistently avoid the subject, or he gives a poor account and shows difficulty in recall, or he claims to have forgotten and requires stimulating in order to remember, or he may have an absolute blank in his memory for certain periods.

Here we see all grades of the result of trying to forget, and the more successful the result the more difficult is the cure; for though the memories are repressed their associated emotions cannot be so dealt with, but remain in consciousness exaggerated and distorted. The dependence of an emotion upon a repressed memory prevents the sufferer from knowing its cause, and the sufferer from an apparently causeless emotion is to be pitied, for he can see no end to his trouble.

A man who was afraid of walking in the dark for fear of falling into holes which he knew only existed as a product of his fancy, affords a simple example of this condition. He said that his fear was absurd, therefore it was useless to point out to him its absurdity; the proper course was to show that it was not absurd, that it had a cause, and that the cause was something in the past which, when recognised, could be reasoned away. Fortunately the cause was easily found by any one with a knowledge of modern war: there was soon brought to light a 'forgotten' memory of his mates being drowned in shell-holes at night, and the fear disappeared as the patient learnt to look his memories in the face and not sink them into his unconscious.

More striking, however, are those cases in which a man forgets all his war experiences, and, though he is ready to believe that he has spent, say, two years in France, has no recollection of them. Such cases are not rare, the loss of memory often including part or all of the patient's previous life. One man could only remember the last three months of his life and failed to recognise his own father, though his memory was subsequently restored; this loss, occurring suddenly, could hardly be in any degree voluntary, though it served the purpose of excluding many horrible memories from his consciousness. Another nervous lad was so constituted that he forgot all incidents that frightened him, only to be haunted by the emotions attached to them. Seeing a steeple-jack fall was forgotten, and produced nightmares for years; a practical joke gave him a terror of the dark; his sister calling to him when burglars were in the house gave him hallucinations of voices; and minor incidents were equally forgotten, each producing its own symptoms. As the individual memories were brought up from his unconscious he went through the fright again, but the associated symptoms soon disappeared.

In these pathological losses of memory, whether for one incident or for a whole period, it is important to note that the patient does not necessarily recognise the incident when he is told of it, just as the lad mentioned above failed to recognise his father when he met him. A patient may in a sleep-walking state act as if performing a definite action, such as bayoneting one of the enemy, and when awake deny all knowledge of such an incident; yet the memory of it may return later with overwhelming emotion. This failure to recognise a personal experience is of great importance in the consideration of some spiritualist phenomena.

It requires little thought to realise that the only memories we try to repress are those that conflict with our other feelings or desires, and their repression is to some extent tolerated by a healthy man and may be regarded to that extent as a normal process.

But in addition to the repression of unpleasant memories there are other ways of forgetting. It has been assumed that each individual has a limit to his capacity for remembering, and that when that limit is reached fresh memories can be stored up only by casting out old ones. Whether that be so or not, it is certain that we can recall to consciousness only a tiny fraction of our past experiences, and no one can say what proportion that fraction bears to the whole contents of the storehouse of the unconscious. Let two men meet and recall old school-days spent together: one memory brings up another, schoolboy phrases and terms of speech appear as it were spontaneously, and by their united efforts the two recall far more than the sum of their recollections before the meeting, and still neither knows how much is left untouched.

The ordinary man reads many books, and each one leaves some impression and has some influence upon his later thoughts, though in time the recollection, not only of the contents of the book, but even of having read it, may fade away. This is the explanation of some cases of literary plagiarism: a previously read phrase comes up from the unconscious, and all recognisable connections with memory having been lost it is greeted as a fresh creation and given rank accordingly.

There is still another type of forgetting: most of us know the man who 'draws the long bow', who embellishes his story and embroiders it with imagined incidents, whilst we listen and wonder how much the narrator himself believes. Fishermen's stories and snake yarns are examples, and one explains the mental process of the story-teller by saying, 'He's told the story so often that at last he believes it himself.' The process is really one of forgetting and is closely allied to the repression of an unpleasant memory, for the man is the victim of a mental conflict: on the one side is his desire to tell a good story, and on the other is his moral complex which forbids a lie, so he solves the conflict by forgetting that the embroideries are inventions. This type is an important one, and what I shall call the 'repression of the knowledge of deceit' plays an important part in the explanation of the abnormal phenomena with which this book deals. In tracing the development of the abnormal we must start with what is nearest the normal, and the man who embroiders his story gives an illustration of the simplest form of this particular repression.

Now, just as memories are repressed because they were repugnant to the other contents of the consciousness, so other complexes may be repugnant and meet the same fate. To be torn by conflicting emotions is the fate of most people at some time or other, and the conflict between two complexes may be solved in various ways. The healthy way is to face the difficulty, to reason it out, and reach a conclusion by which action may be guided; another way, a common one, is to seclude one complex in a logic-tight compartment and so avoid the conflict. The man who uses sharp or shady methods in the city and is a gentle-minded philanthropist in other walks of life is using the latter method, and will produce such rationalisations as 'business is business' when the contents of his different compartments need protection from each other.