Symbols and the Interpretation of Dreams by Carl Jung

In all other branches of science, it is a legitimate procedure to apply an hypothesis to an impersonal object. Psychology, however, inescapably confronts us with the living relationship between two individuals, neither of whom can be divested of his subjectivity or depersonalized in any way. They can mutually agree to deal with a chosen theme in an impersonal, objective manner, but when the whole of the personality becomes the object of their discussion, two individual subjects confront one another and the application of a one-way rule is excluded. Progress is possible only if mutual agreement can be reached. The objectivity of the final result can be established only by comparison with the standards that are generally valid in the social milieu to which the individuals belong, and we must also take their own mental equilibrium, or "sanity," into account. This does not mean that the final result must be the complete collectivization of the individual, for this would be a most unnatural condition. On the contrary, a sane and normal society is one in which people habitually disagree. General agreement is relatively rare outside the sphere of the instinctive qualities. Disagreement functions as a vehicle of mental life in a society, but it is not a goal; agreement is equally important. Because psychology basically depends upon balanced opposites, no judgment can be considered final unless allowance is made for its reversibility. The reason for this peculiarity lies in the fact that there is no standpoint above or outside psychology that would enable us to form a final judgment as to what the psyche is. Everything we can imagine is in a psychic state, i.e., in the state of a conscious representation. To get outside this is the whole difficulty of the physical sciences.

In spite of the fact that the only reality is the individual, some generalities are necessary in order to clarify and classify the empirical material, for it would obviously be impossible to formulate any psychological theory, or to teach it, by describing individuals. As a principle of classification, one can choose any likeness or unlikeness if only it is general enough, be it anatomical, physiological, or psychological. For our purpose, which is mainly concerned with psychology, it will be a psychological one, namely the widespread and easily observable fact that a great number of people are extraverted and others introverted. There is no need for a special explanation of these terms as they have passed into common speech.