The Archetypes and The Collective Unconscious (Collected Works of C.G. Jung Vol.9 Part 1)
By accepting the darkness, the patient has not, to be sure, changed it into light, but she has kindled a light that illuminates the darkness within.
By day no light is needed, and if you don’t know it is night you won’t light one, nor will any light be lit for you unless you have suffered the horror of darkness.
This is not an edifying text but a mere statement of the psychological facts.
The transition from Picture 7 to Picture 8 gives one a working idea of what I mean by “accepting the dark principle.”
It has sometimes been objected that nobody can form a clear conception of what this means, which is regrettable, because it is an ethical problem of the first order. Here, then, is a practical example of this “acceptance,” and I must leave it to the philosophers to puzzle out the ethical aspects of the process. ~Carl Jung, CW 9i, Para 595.