"Right at the beginning you meet the dragon, the chthonic spirit, the devil or, as the alchemists called it, the blackness, the nigredo, and this encounter produces suffering..."
The three phases of alchemical transcendence are nigredo, albedo, and rubedo. Nigredo is "the dark night of the soul", a process of blackening. Albedo is enlightenment, a whitening. Rubedo, the final stage, refers to reddening, the incorporation of enlightenment into one's life.
In alchemy, nigredo is the first stage of achievement the Magnum Opus, wherein the alchemist essays to turn the base into the grand; lead to gold. Nigredo is symbolized by the planet Saturn, and the colour black. Saturn's representation in the physical world is by the basest of metals, lead. The sun is represented by gold. It was thought that, as the planets orbit us, they spin their mineral deposits into the earth.
The nigredo is either present in the prima materia, or is produced by the separation of the elements. One places an egg in the athanor furnace, where there is a symbolic sexual union between the solar male, and the lunar female. The encounter with this blackening causes pain, death, chaos, and putrefaction. Rendered a product of the union, the material is destroyed and turns into blackened, liquid nigredo. The period of nigredo is to last forty days, after which comes the ressurection, albedo.
Jung uses the alchemical process as a metaphor for the spiritual journey toward living in an enlightened manner. In the Jungian psychological model for personal development, the nigredo is the first of three stages of alchemical psychotherapy; it brings the ego into contact with what it fears. The state of nigredo is often caused by a traumatic experience, and signifies the natural period of despair.
The prima materia is the chaotic and unconscious mind, with the requisite potential, dynamic oppositions necessary to achieve the opus. Separation and division are necessary to create synthesis, thereby differentiating one's anima or animus from one's self. To put it plainly, nigredo is the melancholy that makes one slow down, and examine life, to eventually seek therapy, and to witness the shadow side of one's personality. Seeing this shadow makes one encounter one's own powerlessness, guilt, and worthlessness, and work through these with suffering.
One instance of the use of nigredo in Greek myth is when Theseus descends into Hades to rescue Persephone; he is trapped within, and must be rescued by Hercules.
There is a painting, Nigredo, by Anselm Kiefer, in which he inverts a landscape, making it suffer, thereby symbolically restoring the earth's vital functions.
There is also a a fourteen minute music and movement piece of the same name.