DOTLAN EveMaps

The Great Work (Latin: Magnum opus) is an alchemical term for the process of working with the prima materia to create the philosopher's stone. It has been used to describe personal and spiritual transmutation in the Hermetic tradition, attached to laboratory processes and chemical color changes, used as a model for the individuation process, and as a device in art and literature. The magnum opus has been carried forward in New Age and neo-Hermetic movements which sometimes attached new symbolism and significance to the processes. The original process philosophy has four stages:[1][2]

nigredo, the blackening or melanosis
albedo, the whitening or leucosis
citrinitas, the yellowing or xanthosis
rubedo, the reddening, purpling, or iosis

The origin of these four phases can be traced at least as far back as the first century. Zosimus of Panopolis wrote that it was known to Mary the Jewess.[3] The development of black, white, yellow, and red can also be found in the Physika kai Mystika or Pseudo-Democritus, which is often considered to be one of the oldest books on alchemy.[4] After the 15th century, many writers tended to compress citrinitas into rubedo and consider only three stages.[5] Other color stages are sometimes mentioned, most notably the cauda pavonis (peacock's tail) in which an array of colors appear.

The magnum opus had a variety of alchemical symbols attached to it. Birds like the raven, swan, and phoenix could be used to represent the progression through the colors. Similar color changes could be seen in the laboratory, where for example, the blackness of rotting, burnt, or fermenting matter would be associated with nigredo.