What is Alchemy?

Alchemy covers several philosophical traditions spanning some four millennia and several continents, but we can sum it up in this way… Alchemy is the philosophy and practice of liberating a physical substance from its “fixed” physical properties.
Like other sciences, early alchemists used scientific processes, in other words techniques that could be replicated in a lab. But unlike other sciences, you cannot separate the scientific process of alchemy from hermetic principals and spirituality. Those principals and spiritual truths are the basis upon which alchemy stands. It was believed that without achieving a form of enlightenment or inner spiritual revelation, the truths of the universe (which would enable you to transcend temporal reality) would not ever be learned and known to the practitioner. There would be no hope of you transcending the fixed properties of the physical dimension so as to transform something like ordinary metal into gold without gaining access to the higher truths of this universe through spiritual practice and mastery.
The Great Work of Alchemy is often described as a series of four stages, which are represented by colors:
Nigredo- (a blackening or melanosis), which represents a process of putrefaction or decomposition. In this stage, ingredients had to be cleansed and cooked extensively. Internally, this represents a kind of spiritual death and the confronting of one’s shadow aspect.
Albedo- (a whitening or leucosis). The washing away of impurities. The physical subject (such as ingredient) is to be purified and divided into two opposing principles. Internally, this represents re gaining the original purity and receptivity of the soul. Symbolically, it represents the process of washing away the ashes to find the soul.
Citrinitas- (a yellowing or xanthosis). This refers to transmutation and the actual turning of a subject (such as an ingredient) into its highest state such as silver into gold. Internally, this represents awakening…becoming a manifestation of the soul. Becoming a walking embodiment of the soul, rather than a muted reflection of it. It is a process of anything turning into a higher form of itself.
Rubedo- (a reddening, purpling, or iosis). Rubedo refers to the end state; alchemical success. Achievement of the perfected state… The final state of perfection of a subject (such as an ingredient). It can be interpreted as achieving enlightened consciousness and the total fusion of spirit and matter. This stage is often represented by the symbol of the phoenix.

In summation, alchemy can be defined simply as the conscious, intentional process of transmutation, purification, and perfection of _____________ (fill in the blank)
But the most important thing to understand is that there can be no external alchemy without there first being internal alchemy.