Jung developed a relatively simple outline model of the psyche which he thought of as consisting in three concentric spheres. Reading from the outermost inwards, they were the conscious mind, the personal unconscious and the collective or impersonal unconscious. Given the intensity of debate which his thought has aroused over the years, it is important to remember that his model was designed to aid understanding, not to enforce a dogma. Jung himself was well aware that there were no hard boundaries between the various spheres that he had posited. Rather, they were permeable such that energies stirred in any one of the mind's spheres could trouble the quietude of the others. It would not have worried him that some of his successors have, as we shall see, suggested a number of modifications to his original classical model. These include the introduction of a fourth sphere known as the cultural or group unconscious, located between the personal and the collective realms.

Of the two spheres of the unconscious posited by Jung himself, the transpersonal or collective is the one which is remembered as peculiarly his own construct. This is not because the other realm, that of the personal unconscious, lacks importance in the life of human beings. Rather it is because the latter resembles the Freudian subconscious in many of its functions. Jung conceived of it as the repository of contents generated through the circumstances of the individual's existence.