Self in Jungian psychology
The Self in Jungian psychology is one of the Jungian archetypes, signifying the unification of consciousness and unconsciousness in a person, and representing the psyche as a whole. The Self, according to Carl Jung, is realized as the product of individuation, which in his view is the process of integrating one's personality. For Jung, the Self is symbolized by the circle (especially when divided in four quadrants), the square, or the mandala.
What distinguishes Jungian psychology is the idea that there are two centers of the personality.
The ego is the center of consciousness, whereas the Self is the center of the total personality, which includes consciousness, the unconscious, and the ego. The Self is both the whole and the center. While the ego is a self-contained little center of the circle contained within the whole, the Self can be understood as the greater circle.
Emergence from the Self
Jung considered that from birth every individual has an original sense of wholeness - of the Self - but that with development a separate ego-consciousness crystallizes out of the original feeling of unity. This process of ego-differentiation provides the task of the first half of one's life-course, though Jungians also saw psychic health as depending on a periodic return to the sense of Self, something facilitated by the use of myths, initiation ceremonies, and rites of passage. 
Return to the Self: individuation
Once ego-differentiation had been successfully achieved and the individual is securely anchored in the external world, Jung considered that a new task then arose for the second half of life - a return to, and conscious rediscovery of, the Self: individuation. Marie-Louise von Franz states that "The actual processes of individuation - the conscious coming-to-term with one's own inner center (psychic nucleus) or Self - generally begins with a wounding of the personality". The ego reaches an impasse of one sort or another; and has to turn for help to what she termed "a sort of hidden regulating or directing tendency...[an] organizing center" in the personality: "Jung called this center the 'Self' and described it as the totality of the whole psyche, in order to distinguish it from the 'ego', which constitutes only a small part of the psyche".
Under the Self's guidance, a succession of archetypal images emerges, gradually bringing their fragmentary aspects of the Self increasingly closer to its totality. The first to appear, and the closest to the ego, would be the shadow or personal unconscious - something which is at the same time the first representative of the total personality, and which may indeed be at times conflated with the Self. Next to appear would be the Anima and Animus, the soul-image, which again, by a kind of psychological short-cut, may be taken as identical to the whole Self. Ideally however, the animus or anima comes to play a mediatory role between the ego and the Self. The third main archetype to emerge is the Mana figure of the wise old man/woman - a representative of the collective unconscious still closer to the Self.
Thereafter comes the archetype of the Self itself - the last point on the route to self-realization of individuation. In Jung's words, "the Self...embraces ego-consciousness, shadow, anima, and collective unconscious in indeterminable extension. As a totality, the self is a coincidentia oppositorum; it is therefore bright and dark and yet neither". Alternatively, he stated that "the Self is the total, timeless man...who stands for the mutual integration of conscious and unconscious". Jung recognized many dream images as representing the self, including a stone, the world tree, an elephant, and the Christ.
Perils of the Self
Von Franz considered that "the dark side of the Self is the most dangerous thing of all, precisely because the Self is the greatest power in the psyche. It can cause people to 'spin' megalomanic or other delusionary fantasies that catch them up", so that the victim "thinks with mounting excitement that he has grasped the great cosmic riddles; he therefore loses all touch with human reality. 
In everyday life, the Self may be projected onto such powerful figures as the state, God, the universe or fate. When such projections are withdrawn, there can be a destructive inflation of the personality - one potential counterbalance to this being however the social or collective aspects of the Self.
Criticism of the Jungian concept of Self
Fritz Perls may have had the Jungians in mind when he objected that 'many psychologists like to write the self with a capital S, as if the self would be something precious, something extraordinarily valuable. They go at the discovery of the self like a treasure-digging. The self means nothing but this thing as it is defined by otherness'.
Young-Eisendrath and Hall write that 'in Jung's work, self can refer to the notion of inherent subjective individuality, the idea of an abstract center or central ordering principle, and the account of a process developing over time'.
- Josepf L. Henderson, "Ancient Myths and Modern Man" in C. G. Jung ed., Man and his Symbols (London 1978) p. 120
- Zweig, Connie (1991). Meeting the Shadow. Los Angeles: J.P. Tarcher. ISBN 0-87477-618-X. p. 24.
- Henderson, "Myths" p. 120
- Henderson, "Myths" p. 120
- M-L von Franz, "The Process of Individuation" in Jung ed., Symbols p. 169
- von Franz, "Process" p. 161-2
- Jolandi Jacobi, The Psychology of C. G. Jung (London 1968) p. 40
- Barbara Hannah, Striving towards Wholeness (Boston 1988) p. 25
- von Franz "Process" p. 182-3
- C. G. Jung, Alchemical Studies (London 1978) p. 268
- von Franz "Process" p. 193 and p. 195
- J. Jacobi, The Psychology of C. G. Jung (London 1946) p. 115
- C. G. Jung, The Archetypes and the Collective Unconscious (London 1996) p. 183 and p. 187
- Jacobi (1946) p. 118
- C. G. Jung, Mysterium Coniunctionis (London 1963) p. 108n
- C. G .Jung, "Psychology of the Transference", Collected Works Vol. 16 (London 1954) p. 311
- On this last, see "Christ, a Symbol of the Self" in Collected Works Vol. 9ii, p. 36ff. He explicitly says, "Christ exemplifies the archetype of the self." [italics his]
- von Franz, Process, p.234.
- Anthony Stevens, On Jung (London 1990) p. 41
- von Franz, Process, p. 238.
- Fritz Perls, Gestalt Therapy Verbatim (Bantam) p. 8
- Polly Young-Eisendrath/James Albert Hall, Jung's Self-Psychology (1991) p. 5