Naturally, at first, one is inclined to regard such differences as mere individual idiosyncrasies. But anyone with the opportunity of gaining a fundamental knowledge of many men will soon discover that such a far-reaching contrast does not merely concern the individual case, but is a question of typical attitudes, with a universality far greater than a limited psychological experience would at first assume. In reality, as the preceding chapters will have shown, it is a question of a fundamental opposition; at times clear and at times obscure, but always emerging whenever we are dealing with individuals whose personality is in any way pronounced. Such men are found not only among the educated classes, but in every rank of society; with equal distinctness, therefore, our types can be demonstrated among labourers and peasants as among the most differentiated members of a nation. Furthermore, these types over-ride the distinctions of sex, since one finds the same contrasts amongst women of all classes. Such a universal distribution could hardly arise at the instigation of consciousness, ie. as the result of a conscious and deliberate choice of attitude. If this were the case, a definite level of society, linked together by a similar education and environment and, therefore, correspondingly localized, would surely have a majority representation of such an attitude. But the actual facts are just the reverse, for the types have, apparently, quite a random distribution. In the same family one child is introverted, and another extraverted.
— C.G. Jung
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