Nigredo represents the first stage of alchemical transformation, characterized by decomposition, darkness, and the confrontation with base matter. Derived from the Latin niger (black), the term describes the initial phase of the opus alchymicum where substances are broken down through processes like calcination and putrefaction. In psychological terms, particularly within Jungian psychology, nigredo corresponds to the encounter with the shadow - the descent into unconscious material, depression, or crisis that precedes transformation. This blackening stage embodies the principle that true change requires first dissolving existing structures and facing what has been rejected or denied.
The metaphor extends beyond laboratory alchemy into spiritual and creative work. Nigredo describes those necessary periods of confusion, disintegration, or dark night of the soul where old identities or patterns must die before new forms can emerge. Medieval alchemists depicted this stage through symbols of death, ravens, skulls, and decomposing matter - images that capture both literal chemical processes and the psychological experience of dissolution. The stage is considered essential rather than pathological; without the breakdown of nigredo, no genuine individuation or transformation can occur.