Wikipedia
Citrinitas, sometimes referred to as xanthosis, is a term given by alchemists to "yellowness." It was one of the four major stages of the alchemical magnum opus, and literally referred to "transmutation of silver into gold" or "yellowing of the lunar consciousness." In alchemical philosophy, citrinitas stood for the dawning of the "solar light" inherent in one's being, and that the reflective "lunar or soul light" was no longer necessary. The other three alchemical stages were nigredo (blackness), albedo (whiteness), and rubedo (redness).
Psychologist Carl Jung is credited with interpreting the alchemical process as analogous to modern-day psychoanalysis. In the Jungian archetypal schema, nigredo is the Shadow; albedo refers to the anima and animus (contrasexual soul images); citrinitas is the wise old man (or woman) archetype; and rubedo is the Self archetype which has achieved wholeness.