At the Burghülzli Hospital, Jung sought to discover the causes of mental illness by examining brain tissue, and to cure such illnesses by hypnosis. With some colleagues, he developed a word association test (WAT), making a major contribution in standardizing the methods of administration and interpretation. He used several diagnostic indicators: the type of response (eg, a synonym of the stimulus word), incorrect reproduction of the response word, reaction-time, and other test behaviour. While studying verbal behaviour and cognitive processes, Jung's interest was in clinical diagnosis and his theory of what he called 'emotionally toned complexes' (later shortened to 'complexes').

Though Francis Galton (1822-1911) devised the WAT, it was Jung who had the insight that thoughts, feelings, and memories group themselves into dynamic clusters ('complexes'), which function like sub-personalities. Jung was convinced that complexes are evident in both healthy and abnormal states of mind. The voices heard by schizophrenics, the 'spirits' which 'control' mediums in the trance state, and multiple personalities apparent in hysterics were seen as expressions of autonomous complexes. In fact, Jung was the first to apply this knowledge in the treatment of schizophrenia.

Jung's work on the WAT and theory of complexes contributed to his study of unconscious contents. Later, his observations of the contents of patient's dreams, hallucinations and delusions provided data for his hypothesis of the existence of collective (archetypal) material in the unconscious psyche: complexes being the means through which archetypes manifest themselves in the personal unconscious.

It was through studying the polarity and dynamics of the psyche, and the relationship between the movements of psychic energy along certain paths and their differences in their effect on individual personalities and human interactions, that gave rise to Jung's psychological typology¹.

Freud and Jung

In 1900, Jung (aged 25) read Freud's The Interpretation of Dreams, the year of its publication. But it was three years later before he realised how Freud's work linked up with the mechanism of repression which he had noted in his word association experiments. Freud was persona non grata in the academic world at the time and Jung was warned of endangering his own academic career, and risking ridicule from colleagues, should he decide to ally himself with and defend Freud's theories. Though having serious misgivings about Freud's dogmatic idea that all neuroses were caused by sexual repression or trauma (Jung believing it played a subordinate part), it was in the spirit of seeking empirical truth that Jung began a seven-year period of collaboration with Freud, mostly by correspondence.

The two men eventually met in February 1907, in Vienna, where they talked virtually non-stop for 13 hours. Thereafter, Freud began to groom Jung as his successor and leader of the psychoanalytic movement. Jung, in turn, viewed Freud as a positive 'father' figure who was intellectually courageous, something his own father was not. However, this father-son relationship was fated not to last, especially since the prospect of becoming the 'crown prince' meant sacrificing his intellectual independence. Nevertheless, Jung became the first president of the International Psychoanalytic Association (IPA) and chief editor of the Jahrbuch, the first psychoanalytic journal.

During subsequent meetings - including the journey, in 1909, to Clark University, Worcester, Massachusetts and at Congresses of the IPA - Jung became increasingly aware that his conceptions significantly differed from Freud's. Jung found Freud's theory of dream interpretation too rigid and reductive, making him blind towards the paradox and ambiguity of unconscious contents. His intellectual doubts concerned the way Freud overgeneralised his theories, especially the theory that all neuroses had their roots in polymorphous, perverse, infantile sexuality.

Four years after becoming president of the IPA in 1910, Jung resigned his office, after irreconcilable differences with Freud over the 'heretical' publication of his The Psychology of the Unconscious². This book, on the nature of the libido, was an outright rejection of Freud's view of it as exclusively sexual. It consisted of Jung's reflections on a series of fantasies of an American patient, named Miss Miller, and used mythological parallels related to these fantasies. Jung hypothesised that libido is non-specific psychic energy, arguing that sexuality was but one form in which this energy can be channelled³.

Jung also challenged another basic tenet of psychoanalytic theory, notably the Oedipus or Electra complex. While acknowledging that boys become powerfully attached to their mothers, and potentially bring them into conflict with their fathers, Jung denied that either attachment or conflict was inevitably sexual. On the contrary, the son's longing for his mother (through incestuous desires) was spiritual rather than physical or sexual, reflecting a need for a kind of psychological renewal⁴. By way of illustration, Jung examined the archetypal theme of the hero's struggle for deliverance from the 'terrible' mother. He used the solar myth of 'the night sea journey' to show how the masculine heroic ego, by entering the darkness of the mother's womb, undergoes a rebirth or transformation of consciousness. Jonah and the whale, Osiris cast adrift in a chest, and Noah's journey over the flood are all mythological dramas that symbolise this necessary but terrifying ordeal in the body of the mother. Jung instinctively knew that only by facing this ordeal of initiation, only by entering the womb of change and dying to the past, can a new pathway to life be opened.

Jung concluded that our deepest needs are for meaning and purpose; that is, humans are by nature religious⁵, and that psychological, rather than actual, incest was the means to channel libido into new forms and to develop spiritually. Over time, Jung saw religious practice as a fundamental archetypal need and, deprived of its symbolism, individuals were cut off from meaning, and societies were doomed to die. To Jung the problem of the second half of life was essentially religious.

Total disillusionment with Freud came during the trip to Clark University. Lasting seven weeks, the two men spent time analysing each other's dreams. On one occasion, Freud refused to share his associations to a dream, stating that it would undermine his authority. To Jung, placing personal authority over truth foreshadowed the end of their relationship. On another important occasion, Freud's attempt to interpret one of Jung's dreams as wish fulfilment conflicted with Jung's view that the dream contained collective content. The dream was of...

a two storey house that Jung did not know, but was 'his house'. The upper storey was furnished in rococo style; the lower 'darker' floor had medieval furnishings. There was also a cellar containing the remains of a primitive culture, including two skulls⁶.

In looking for the wish fulfilment, Freud assumed that the skulls represented wishes for the death of two persons close to Jung. In contrast, Jung associated the skulls with two he had studied in paleontology, and he saw the house as an image of the psyche that included beneath 20th Century culture a primitive level 'which can scarcely be reached or illuminated by consciousness'⁷.

This dream was his first inkling of a collective a priori essence beneath the personal psyche, which he later recognised as forms of instincts or archetypes. The concept of the collective psyche, or unconscious, was the subject of the book, The Psychology of the Unconscious, that so alienated Freud. By contributing both to the development of Jung's theory of the unconscious and to his controversy with Freud, this single dream was instrumental in the subsequent break.