When a mass of ideas and emotions collects round a common nucleus in the mind, a system is formed which will react in a particular way to incoming stimuli. This system is called a complex. The conception of complexes is due to the work of Dr. Jung, and he has shown how the reactions of the psyche are influenced by the presence in it of complexes. If a man commits a murder and says nothing about it, there collects round the murder-nucleus a mass of thoughts, ideas, and feelings. A complex is formed. The existence of this guilt-complex will produce an acute situation in the man's mind. What is he going to do with it? It will find itself in opposition with other complexes that centre about social duties and good conduct. He may solve his conflict in various ways.

He may push the guilt complex out of consciousness into the unconscious. In this case the guilt-complex will manifest itself in dreams. We may expect him to experience nightmares in which the incidents of the murder will be revived. He may follow another course in which he thrusts out the acquired moral complexes, from consciousness and dwells alone with the murder-complex. This will mean a profound degradation of the conscious life, and he will experience in his dreams a return of the banished moral complexes in powerful symbols. A third course is possible. Fantasy may play a leading part in the attempt to reconcile the conflicting complexes. It may, for example, construct a theory in his mind that he never committed a murder at all. This fantasy may become very elaborate and gradually extend over the whole conscious field. The murder-complex and the acquired moral complexes will pass into the unconscious as the fantasy grows, until at last the man will live wholly in his fantasy. He will be insane. The sources of his malady will be the two powerful and opposing complexes in the unconscious which will feed his fantasy.

There are complexes common to everyone. Round the idea of the father and round the idea of the mother—or those people who stand in the place of the father and the mother—the child collects a great mass of memories, feelings, and thoughts. These will form respectively the father-complex and the mother-complex. In typical cases these complexes are not wholly compatible when they exist together in consciousness, for they are associated with two different views of life. These complexes, which are normally found in everyone, may develop to an abnormal extent. A person may possess a father-complex that dominates him. He is, as it were, not his own master. What he, as an individual, seeks to do, and what the father-complex makes him do may be two very different things. A person may practically live in his or her father-complex, in which case there would be a corresponding identification with the father in reality; or if the father be dead, an identification with all the political, religious, and social views that he expressed in life. Such a person is an imitation. Provided that the conditions under which the father lived still exist, the imitation may be effective. If the conditions alter and new ideas permeate the environment, the person will be unable to make an adaptation to them unless the father-complex is moved from its central position in consciousness. It comes about naturally that people who are completely dominated by the father-complex continually look into the past and not into the future. They may become conscious of the father-complex and separate themselves from it. In such a case, although the complex still exists, a life of personal independence becomes partially attainable.

When a person lives entirely in a complex he appears to other people to be biassed. He is the man of one idea and of one book. The expression of interest will be only possible through one pattern. This may not always be bad, because the complex may be connected with a progressive idea. The man may conceive of some injustice existing in society and amass round this idea a great quantity of thoughts and feelings. If, then, he lives in this complex solely, he may bring about some reform that is valuable to humanity. But people will regard him as biassed.

The influence of complexes upon the reactions of the psyche was studied by Dr. Jung by means of the association method. If a person is asked to give an immediate association with a word, a certain time elapses before the association is given. If a man is asked to give an association with the word rose, he may, after the space of a second, say red. But if he is in love with a girl of this name, the word will cause the whole system of feelings and ideas centred round the girl to vibrate. This may cause him to blush or stammer or hesitate. He may be at a loss to find any single association, and the result will be that a considerable time will pass before he says anything. This delayed reaction of the psyche will point to the existence of a complex. It is thus possible by selecting a list of test words and asking a patient to make associations with each one in turn to gain some idea of the main complexes in his psyche. The disadvantages of this method he in the kind of inquisitorial atmosphere it produces between the patient and the physician. The use of any method that borders on the mechanical gives an unnatural result. Some investigators have sought, by the aid of electrical and clockwork devices, to record the reaction time of associations with minute accuracy, without taking into consideration that by this method they interpose machinery between themselves and the patient.

At different times of the day different complexes tend to enter into the conscious field. In general the morning brings the business or practical complexes into a central position, and interest discharges itself through them. In the evening social complexes dominate the field, and interest flows through them. The process is comparable to different shdes being put into a magic lantern altering the pattern of the light-energy on the screen. It is like different stencils intervening between the ink and the paper. But it must not be thought that a complex is shallow ; its roots lie deeply in the psyche, and its revelation in consciousness is only partial. When a complex is in a central position and interest is discharging itself through it, any incident that tends to push it out into a marginal position may cause irritability. Thus a gourmet at dinner when he is expressing himself successfully through his food-complexes, is likely to be annoyed if he is called away on business. The outpouring of interest is suddenly checked. Another complex obtrudes on consciousness, through which interest flows with difficulty. Tension must then occur, and this the man experiences as a sense of irritation. Or, if a man with large social complexes goes out to dinner and finds that the conversation is dominated by a professor who explains the differences between the skull of the chimpanzee and the skull of palaeolithic man, it is only natural that he should get irritable. He has no comparative-anatomy-complex through which he can express himself. His outflow of interest is checked, save through the channel of food. He therefore devotes himself to eating in his endeavour to drain off part of the tension, while the other part manifests itself in him as irritability. Now supposing that the man had been invited to dine with the professor alone. What would his feelings have been during dinner ? I think I am right in saying that, in such a case, he would not feel irritable, but only extremely bored and wearied. At the end of dinner he would feel relief. But at the end of the dinner-party he would still feel irritable.

If we look at this from the point of view of complexes, what explanation is to be found which will account for these two differing sensations ? Why should it arise that we sometimes feel weariness and sometimes feel irritability in positions where the outflow of interest is checked ?

In the case of the man with the large social complex his irritability is caused by the fact that a certain expected outflow of interest is baulked. Expression through the social complex is checked by the professor's conversation. But for the professor the environment of the dinner-party is favourable to an egotistical expression, in the form of personal success with the other guests. On the other hand, in the case of the dinner with the professor alone the environment is not favourable.

It does not call up any complex in the man's psyche. He cannot express himself egotistically. We can see, then, that one explanation of irritability may lie in the existence of a complex which the environment stimulates, but cannot satisfy. And in the case of weariness we may see a situation that stimulates no complexes and therefore affords no familiar channel of expression. These conclusions may appear obvious, but they may serve to illustrate one aspect of complexes.* It affords a rich field of interest to anyone, whether neurotic or hot, to study outbursts of irritation in the light of complexes.

* The idea of the complex has been recognized in various psychological systems. Herbart postulated apperception-masses. William James described the many selves within the personality.