The ultimate goal of alchemy is a process known as the great work, or the magnum opus in Latin. This involves spiritual transformation, involving the shedding of impurities, the joining of opposites, and the refinement of materials. Exactly what the end result of this profound transformation varies from author to author: self-realization, communion with divinity, fulfillment of purpose, and so forth.
Indeed, part of the transformation may involve better understanding what the end goal even is. After all, it is accepted that few if any alchemists have ever reached their goal. The pursuit of the goal is every bit as important as the goal itself.
AllegoriesComplex philosophical beliefs are often communicated through allegory. The Greek philosopher Plato is famous for repeatedly using allegory in his works.
Plato believed that ultimate reality was very different from what most people perceived as reality, which was actually a false, misleading and corrupt version of true reality. He compared this corrupt reality to what people would see if they were chained facing a wall in a cave: flickering shadows. He then compares understanding of the ultimate reality with, first, understanding that the shadows were actually formed from fire and objects moving in front of it, and, second, getting out of the cave and seeing the rest of the world. This still doesn't tell you what the ultimate reality is, but it does give you a sense of how much more complex it is than mundane reality and how poorly Plato feels about the average person's perception of the world.
The main reason Plato uses allegories is because his topics are highly complex and abstract. He can't simply describe the ultimate reality. (Not only is it indescribable, but even Plato himself would not even be able to fully understand it, although he thought he understood much more of it than the average person.) He can, however, compare his ideas with less abstract examples, allowing readers to begin to grasp basic meaning and then add to that learning through continued study.
Alchemy works similarly. Processes and outcomes are rich with allegory, compared to animals, people, objects, pagan deities and more. Imagery is common, producing rich images that appear random and bizarre to the untrained eye.
ChemistryAlchemy is most commonly described in chemical terms, and alchemists were also frequently chemists. The common concept of turning lead into gold is about refining the coarse and common into the rare and the perfect, for example.
Nigredo, Albedo and RubedoAlchemists write of many, many processes involved in the great work. Moreover, different alchemists have different views on the subject, as is always the case in esoteric studies. However, generally speaking, we can summarize things into three great stages, particularly when working from materials from around the 16th century, when a great amount of alchemical material was being produced.
Nigredo, or blackening, is decomposition and reduction. This process breaks complex things back down to its most basic components.
Albedo, or whitening, is a purification process which leaves the alchemists with only the purest essences which which to work. The process of nigredo and albedo is a cycle potentially performed many times as the self is broken down and purified again and again. These essences are ultimately reduced to two opposites, often described as the red king and the white queen.
The rubedo, or reddening stage is when true transformation occurs: the revelations previously uncovered is brought to reality, and a true union of opposites occurs, manifesting in a truly united being ultimately aware of and in harmony with all aspects of itself. The final result of this is the rebis, described as a spiritual hermaphrodite and often depicted as a two-headed being.