The great problems of life — sexuality, of course, among others — are always related to the primordial images of the collective unconscious. These images are really balancing or compensating factors which correspond with the problems life presents in actuality. This is not to be marvelled at, since these images are deposits representing the accumulated experience of thousands of years of struggle for adaptation and existence.

Ch. 5, p. 271 - Psychological Types, or, The Psychology of Individuation (1921)