To H. J. Barrett
Dear Mr. Barrett, 27 December 1956
Thank you for your interesting letter. It is indeed an important question, the question of sleep and dream.
As far as my knowledge goes we are aware in dreams of our other life that consists in the first place of all the things we have not yet lived or experienced in the flesh.
Beyond that material we are also aware of things we never can realize in the flesh and not in this life.
Things belonging to the past of mankind and presumably to its future also.
The latter can be realized only very rarely as future events, because we have no means, or very few, to recognize and identify future events before they have happened, as we also cannot understand thoughts we never had before.
All the things which are not yet realized in our daylight experience are in a peculiar state, namely in the condition of living and autonomous figures, sometimes as if spirits of the dead, sometimes as if former incarnations.
These formulations are probably auxiliary means supplied by our unconscious mind to express forms of psychic existence we do not really understand.
I am sorry my time does not allow me to comment in detail about your experiences.
I hope my general observations will help you to a certain extent.
C.G. Jung ~Carl Jung, Letters Vol. II, Page 341