The Mutus Liber, or Mute Book, is a Hermetic philosophical work published in La Rochelle in 1677. It ranks amongst the major books on alchemy in Early Modern literature, just as much as does Atalanta Fugiens by Michael Maier. It has been reprinted numerous times.
Mutus Liber cover
In alchemy, the Magnum Opus or Great Work is a 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:nigredo, the blackening or melanosis
albedo, the whitening or leucosis
citrinitas, the yellowing or xanthosis
rubedo, the reddening, purpling, or iosis
Colors of the magnum opus seen on the breastplate of a figure from Splendor Solis