“The science of the I Ching…is based on what I have tentatively called the synchronistic principle. My occupation with the psychology of unconscious process long ago necessitated my casting around for another explanatory principle, because the causality principle seemed to me inadequate for the explanation of certain remarkable phenomena of the unconscious.
Thus I found there are psychic parallelisms which cannot be related to each other causally, but which must stand in another sort of consciousness. This connection seemed to me to lie mainly in the relative simultaneity of the events, therefore the expression ‘synchronistic’.
It seems, indeed, as though time, far from being an abstraction, is a concrete continuum which contains qualities or basic conditions manifesting themselves simultaneously in various places in a way not to be explained by causal parallelism, as, for example, in cases of the coincident appearance of identical thoughts, symbols, or psychic states.”
The Secret of the Golden Flower