Short answer
The ego, the collective unconscious and the persona collectively help the person to self-actualise and reach individuation through the elements of the psyche being in harmony with each other.
Long answer
A lot of what I am providing in this answer has been put together using my knowledge of Jungian Psychology from my 3 year Psychotherapy course I am sudying at Reading University and information within Wolberg (2013). Anything not referenced here is from the Wolberg book.
Individuation
Let's first of all define the word Individuation
In the broadest possible way, individuation can be defined as the achievement of self-actualization through a process of integrating the conscious and the unconscious. Once again, any accurate understanding of Jung should come from [Jung]. (Source: Journal Psyche)
Self Actualisation is a term coined by Abraham Maslow with his Hierarchy of Needs, and refers to having a fulfilment and mastery of all your needs from the simplest to the more complex.
Jung, the Psyche, and the Collective and Personal Unconscious
According to Carl Gustav Jung, the psyche is compartmentalised in a different way than Freud proposed. He divided the psyche into
- a superficial part, the persona
a social mask assumed by the individual, made up of social interests and sanctions
- a less superficial aspect, the ego
which is only to some extent conscious and reflects past-personal experiences, and
- a deeply unconscious part
which has within it the collective unconscious and contained archetypes (Creator, Caregiver, Ruler, Jester...).
Difficulties occur when there is a lack of harmony among the persona, the ego, and the collective unconscious. Jung conceived of the idea that baser elements of the soul were present in the collective unconscious, and he characterised these as “the Shadow.”
The psychic reality of the situation created by the psychic images, developed in the conscious, create complexes [e.g. Inferiority Complex] and the issues, and their connected experiences are repressed or suppressed into the "shadow lands" of the personal unconscious.
Jung also believed that the collective unconscious contained
creative fountains of energy. Primitive fears and other untoward manifestations of the unconscious invaded the patient’s conscious mind and created tensions and various neurotic symptoms that were attempts at self-cure. The collective unconscious, unleashed, constituted a source of danger for the person.
The 2 different human characters
Jung also evolved a theory of character, whereby people are divided into two types: introverts and extroverts. The introvert’s interests centred on himself or herself; the extrovert’s interests were on the external world.
A human being, said Jung, had an innate religious craving which powered the need for self-realization. There was, he explained, no retreat from life’s burdens other than to find refuge in spiritual strivings with “acceptance of the irrational and unbelievable.” By experiencing the collective unconscious, an individual no longer would experience personal sorrow "but the sorrow of the world, no longer a personal isolating pain, but pain without bitterness, binding all human beings together.” We are brought “back to ourselves as an existing, living something, stretched as it were between two worlds of images, from which forces proceed that are only dimly discerned but are all the more clearly felt. This something, though strange to us, is yet so near, it is altogether ourselves and yet unrecognizable, a virtual middlepoint of such a mysterious constitution that it can demand anything, relationship with animals and with gods, with crystals and with stars.” These ideas were elaborated by Jung (1961) in his last book, Memories, Dreams, Reflections, a fascinating autobiographical document that explains his relationship with Freud and gives us a broader understanding of the essence and meaning of his work.
Putting it together for psychotherapy
During Jungian psychoanalytic therapy...
an effort is made to explore “archetypes” in order to determine how these imprints contaminate the patient’s present life and interfere with self-development and self-realization (individuation). Bringing the individual into contact with his or her collective unconscious is said to help liberate creative forces that will have a constructive effect on adjustment. Once non-conscious elements are recognized, an attempt is made to guide the patient actively into a productive relationship with the unconscious.
References
Wolberg, L. R., 2013. The Technique of Psychotherapy - Fourth Edition,
Chevy Chase, MD:International Psychotherapy Institute E-Books
Available free from http://www.freepsychotherapybooks.org
For further in-depth information on Jungian Analytical Psychology:
Frieda Fordham (1991) An Introduction to Jung's Psychology, 3rd Revised Edition,
London:Penguin Books Ltd. (ISBN-13: 978-0140135688)
Carl Gustav Jung (1969) The Archetypes and the Collective Unconscious (Collected Works of C. G. Jung)
2nd edition translation in 1981 by Gerhard Adler & R.F.C. Hull. Princeton: Princeton University Press (ISBN-13: 978-0691018331)
exact same edition also printed in 1991 by London:Routledge (ISBN-13: 978-0415058445)