Jung's theory of psychological types is the culmination of his previous psychological theories; and these are so closely interwoven into-its texture, that an attempt to separate them from it would inevitably destroy the whole fabric. The acceptance of the type theory implies, therefore, an acquiescence at least in the theories out of which'it arose. None the less, it is just in its rudimentary state that one finds the theory least acceptable. One may applaud the stroke of genius whereby the psychological phenomena of hysteria and of dementia praecox are accounted for by the assumption that in one case the psychical energy is outwardly directed, and in the other inwardly, without going so far as to agree that the contrast is one that has its necessary counterpart in normal life.

I may illustrate that in this way. Jung's insight into human psychology appears to be due in large measure to his unique intuitive powers. His whole psychological outlook is permeated with intuitively sensed knowledge. It is this that makes it so very difficult for anyone to apprehend his teaching and accounts for the fact that he has been styled a 'mystic' rather than a scientist. He is an intuitive who has been absorbed in the problems of the inner life; and if I had to hazard an opinion of his own type category, I Would .call him an Introvert Intuition type. For me, the fact he is intuitive is more important than that he is an Introvert. His intuition will always be in evidence, whilst his introversion will be shewn only when the needs of the situation call it forth.

The theory of psychological types is an abstract theory. Jung tells us that there is no question of deductio a priori in his conception, but that it represents merely a deductive presentation of empirically gained understanding. Add to 'empirically', 'intuitively', and you have the explanation of the difficulty of applying the theory in practice. Such intuitive apprehension as Jung possesses Faust be exceedingly rare. I must confess that I have not been able to apply this theory in psychiatrical work, save in a very few instances, and when I hear people talking glibly of Jung's theories and of the necessity of determining a type category before applying treatment, I suspect that -their observations have been superficial and their assumptions ill -grounded.

This is not to deny that typical attitudes such as Jung has portrayed exist. They assuredly do. But typical attitudes are rare. One bears in mind that Jung says that the preponderance of the one mechanism over the other constitutes the attitude, but seldom is there such preponderance. Adaptation to circumstances, both of the outer world and the inner life, necessarily calls for the use of both mechanisms. No doubt the outer world is all too imperious in its demands and the inner life is apt in consequence to suffer neglect, and in our modern life extraversion plays too important a role. But there are many secret sources of nourishment of the inner life also, not by any means self-evident, which help to right the balance.

We know what is meant in popular parlance by extraverts and introverts, and we can see that in a rough general way mankind might be so classified. But we have to transcend popular phraseology and determine scientifically who are the real extraverts and the real introverts. We have to translate an abstract definition into concrete terms and to distinguish accurately between true types and false. And when we do this, when we search for the real extravert and the real introvert, we seldom succeed. Theoretically the preponderance of either mechanism would constitute an attitude, but practically this may be so slight as to make us prefer to regard persons as normally both extraverted and introverted.

The extraversion and introversion which occur in mania and in melancholia respectively have every bit as much right to be regarded as the true counterparts of normal extraversion and introversion. According to the hysteria -dementia praecox contrast, attitudes, exclusive of each other, are to be sought for; for the hysteric does not suffer from dementia praecox nor the precocious dement from hysteria. Whereas if the contrast had been made between mania and melancholia , and a theory had been built upon the contrast, mechanisms occurring in the selfsame person would have received more attention than attitudes occurring in different persons.

It was in order to bring greater clarity to type diagnosis, that Jung found it necessary to introduce the consideration of psychological functions into his theory; and it is just this introduction that has made these functions loom more largely in our vision and has caused the general attitudes to recede into the dimmer background. For, despite the difficulties of isolating these functions, it is true that the predominance of one function over another may be so marked in a person as to make it much more important that we should recognise its presence than be able to recognise a general attitude.

It will be remembered that Jung could not allow his early theory to remain in the form in which he had propounded it. Further analysis revealed that the feeling type could not be identified with the extravert, or the thinking type with the introvert; and so recourse-was had to still deeper investigation,. and we are now told that in all doubtful cases - and they would appear to be numerous - an exhaustive. examination of the psychological functions of thinking, feeling, sensation and intuition is required before the category can be determined.

Whether the theory of psychological types stand or fall is of little moment as compared with the unrivalled insight into the workings of the human mind which Jung's psychological writings in general, and his "Psychological Types' in particular, afford. Jung's great intellectual gifts have been of the utmost service to psychology. More than any other man, he has penetrated into the darkest recesses of the human mind, and has illumined these with the superb lighting of his imagination.

And what, after all, do we know about a man when we know that he is, say, an intuitive introvert? I believe Coleridge to have been such;.and yet how utterly unlike are Jung and Coleridge. It is the psychology of the individual that matters, not the designation of his type, and the especial value of Jung's type psychology is just the fact that it enables us to have a richer and deeper knowledge of individual psychology.